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Cai F, Robertson IM, Kampourakis T, Klein BA, Sykes BD. The Role of Electrostatics in the Mechanism of Cardiac Thin Filament Based Sensitizers. ACS Chem Biol 2020; 15:2289-2298. [PMID: 32633482 DOI: 10.1021/acschembio.0c00519] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/21/2023]
Abstract
Heart muscle contraction is regulated by calcium binding to cardiac troponin C. This induces troponin I (cTnI) switch region binding to the regulatory domain of troponin C (cNTnC), pulling the cTnI inhibitory region off actin and triggering muscle contraction. Small molecules targeting this cNTnC-cTnI interface have potential in the treatment of heart disease. Most of these have an aromatic core which binds to the hydrophobic core of cNTnC, and a polar and often charged 'tail'. The calmodulin antagonist W7 is unique in that it acts as calcium desensitizer. W7 binds to the interface of cNTnC and cTnI switch region and weakens cTnI binding, possibly by electrostatic repulsion between the positively charged terminal amino group of W7 and the positively charged RRVR144-147 region of cTnI. To evaluate the role of electrostatics, we synthesized A7, where the amino group of W7 was replaced with a carboxyl group. We determined the high-resolution solution NMR structure of A7 bound to a cNTnC-cTnI chimera. The structure shows that A7 does not change the overall conformation of the cNTnC-cTnI interface, and the naphthalene ring of A7 sits in the same hydrophobic pocket as that of W7, but the charged tail takes a different route to the surface of the complex, especially with respect to the position of the switch region of cTnI. We measured the affinities of A7 for cNTnC and the cNTnC-cTnI complex and that of the cTnI switch peptide for the cNTnC-A7 complex. We also compared the binding of W7 and A7 for two cNTnC-cTnI chimeras, differing in the presence or absence of the RRVR region of cTnI. A7 decreased the binding affinity of cTnI to cNTnC substantially less than W7 and bound more tightly to the more positively charged chimera. We tested the effects of W7 and A7 on the force-calcium relation of demembranated rat right ventricular trabeculae and demonstrated that A7 has a much weaker desensitization effect than W7. We also synthesized A6, which has one less methylene group on the hydrocarbon chain than A7. A6 did not affect binding of cTnI switch peptide nor change the calcium sensitivity of ventricular trabeculae. These results suggest that the negative inotropic effect of W7 may result from a combination of electrostatic repulsion and steric hindrance with cTnI.
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Affiliation(s)
- Fangze Cai
- Department of Biochemistry, University of Alberta, Edmonton, AB T6G 2R3, Canada
| | - Ian M. Robertson
- Ministry of Health, Government of Alberta, Edmonton, AB T5J 1S6, Canada
| | - Thomas Kampourakis
- Randall Centre for Cell and Molecular Biophysics, King’s College London, London SE1 1UL, United Kingdom
| | - Brittney A. Klein
- Department of Biochemistry, University of Alberta, Edmonton, AB T6G 2R3, Canada
| | - Brian D. Sykes
- Department of Biochemistry, University of Alberta, Edmonton, AB T6G 2R3, Canada
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Robertson IM, Klein BA, Sykes BD. Optimizing fluorine labelling for 19F solid-state NMR in oriented biological systems. J Biomol NMR 2020; 74:1-7. [PMID: 31912345 DOI: 10.1007/s10858-019-00296-8] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/12/2019] [Accepted: 12/31/2019] [Indexed: 06/10/2023]
Abstract
When planning a fluorine labeling strategy for 19F solid state NMR (ssNMR) studies of the structure and/or mobility of fluorine labeled compounds in situ in an oriented biological system, it is important to characterize the NMR properties of the label. This manuscript focuses on the characterization of a selection of aromatic fluorine compounds in dimyristoylphosphatidylcholine bilayers using 19F ssNMR from the standpoint of determining the optimum arrangement of fluorine nuclei on a pendant aromatic ring before incorporation into more complex biological systems.
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Affiliation(s)
- Ian M Robertson
- Ministry of Health, Government of Alberta, Edmonton, AB, T5J 1S6, Canada
| | - Brittney A Klein
- Department of Biochemistry, University of Alberta, Edmonton, AB, T6G2H7, Canada
| | - Brian D Sykes
- Department of Biochemistry, University of Alberta, Edmonton, AB, T6G2H7, Canada.
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Matsumura N, Zordoky BN, Robertson IM, Hamza SM, Parajuli N, Soltys CLM, Beker DL, Grant MK, Razzoli M, Bartolomucci A, Dyck JRB. Co-administration of resveratrol with doxorubicin in young mice attenuates detrimental late-occurring cardiovascular changes. Cardiovasc Res 2019; 114:1350-1359. [PMID: 29566148 DOI: 10.1093/cvr/cvy064] [Citation(s) in RCA: 38] [Impact Index Per Article: 7.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/26/2017] [Accepted: 03/15/2018] [Indexed: 12/23/2022] Open
Abstract
Aims Doxorubicin (DOX) is among the most effective chemotherapies used in paediatric cancer patients. However, the clinical utility of DOX is offset by its well-known cardiotoxicity, which often does not appear until later in life. Since hypertension significantly increases the risk of late-onset heart failure in childhood cancer survivors, we investigated whether juvenile DOX exposure impairs the ability to adapt to angiotensin II (Ang II)-induced hypertension later in life and tested a treatment that could prevent this. Methods and results Five-week-old male mice were administered a low dose of DOX (4 mg/kg) or saline once a week for 3 weeks and then allowed to recover for 5 weeks. Following the 5-week recovery period, mice were infused with Ang II or saline for 2 weeks. In another cohort, mice were fed chow containing 0.4% resveratrol 1 week before, during, and 1 week after the DOX administrations. One week after the last DOX administration, p38 mitogen-activated protein kinase (MAPK) was activated in hearts of DOX-treated mice demonstrating molecular signs of cardiac stress; yet, there was no change in cardiac function between groups. However, DOX-treated mice failed to develop compensatory cardiac hypertrophy in response to Ang II-induced hypertension later in life. Of importance, mice receiving DOX with resveratrol co-administration displayed normalization in p38 MAPK activation in the heart and a restored capacity for cardiac hypertrophy in response to Ang II-induced hypertension. Conclusion We have developed a juvenile mouse model of DOX-induced cardiotoxicity that displays no immediate overt physiological dysfunction; but, leads to an impaired ability of the heart to adapt to hypertension later in life. We also show that co-administration of resveratrol during DOX treatment was sufficient to normalize molecular markers of cardiotoxicity and restore the ability of the heart to undergo adaptive remodelling in response to hypertension later in life.
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Affiliation(s)
- Nobutoshi Matsumura
- Department of Pediatrics, Faculty of Medicine and Dentistry, Cardiovascular Research Centre, University of Alberta, 87th Avenue and 112 Street, Edmonton, Alberta T6G 2S2, Canada.,Division of Cardiovascular Surgery, Tohoku University Graduate School of Medicine 1-1, Seiryo-machi, Aoba-ku, Sendai, Miyagi, 980-8574, Japan
| | - Beshay N Zordoky
- Department of Pediatrics, Faculty of Medicine and Dentistry, Cardiovascular Research Centre, University of Alberta, 87th Avenue and 112 Street, Edmonton, Alberta T6G 2S2, Canada.,Department of Experimental and Clinical Pharmacology, College of Pharmacy, University of Minnesota, 308 Harvard Street S.E., Minneapolis, MN 55455, USA
| | - Ian M Robertson
- Department of Pediatrics, Faculty of Medicine and Dentistry, Cardiovascular Research Centre, University of Alberta, 87th Avenue and 112 Street, Edmonton, Alberta T6G 2S2, Canada
| | - Shereen M Hamza
- Department of Pediatrics, Faculty of Medicine and Dentistry, Cardiovascular Research Centre, University of Alberta, 87th Avenue and 112 Street, Edmonton, Alberta T6G 2S2, Canada
| | - Nirmal Parajuli
- Department of Medicine, Cardiovascular Research Centre, Faculty of Medicine and Dentistry, University of Alberta, 87th Avenue and 112 Street, Edmonton, Alberta T6G 2S2, Canada
| | - Carrie-Lynn M Soltys
- Department of Pediatrics, Faculty of Medicine and Dentistry, Cardiovascular Research Centre, University of Alberta, 87th Avenue and 112 Street, Edmonton, Alberta T6G 2S2, Canada
| | - Donna L Beker
- Department of Pediatrics, Faculty of Medicine and Dentistry, Cardiovascular Research Centre, University of Alberta, 87th Avenue and 112 Street, Edmonton, Alberta T6G 2S2, Canada
| | - Marianne K Grant
- Department of Experimental and Clinical Pharmacology, College of Pharmacy, University of Minnesota, 308 Harvard Street S.E., Minneapolis, MN 55455, USA
| | - Maria Razzoli
- Department of Integrative Biology and Physiology, Medical School, University of Minnesota, 2231 6th Street S.E. Minneapolis, MN 55455, USA
| | - Alessandro Bartolomucci
- Department of Integrative Biology and Physiology, Medical School, University of Minnesota, 2231 6th Street S.E. Minneapolis, MN 55455, USA
| | - Jason R B Dyck
- Department of Pediatrics, Faculty of Medicine and Dentistry, Cardiovascular Research Centre, University of Alberta, 87th Avenue and 112 Street, Edmonton, Alberta T6G 2S2, Canada
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Klein BA, Robertson IM, Reiz B, Kampourakis T, Li L, Sykes BD. Thioimidate Bond Formation between Cardiac Troponin C and Nitrile-containing Compounds. ACS Med Chem Lett 2019; 10:1007-1012. [PMID: 32426091 PMCID: PMC7227049 DOI: 10.1021/acsmedchemlett.9b00168] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/12/2019] [Accepted: 05/15/2019] [Indexed: 12/16/2022] Open
Abstract
We have investigated the mechanism and reactivity of covalent bond formation between cysteine-84 of the regulatory domain of cardiac troponin C and compounds containing a nitrile moiety similar to the calcium sensitizer levosimendan. The results of modifications to the levosimendan framework ranged from a large increase in covalent bond formation to complete inactivity. We present the biological activity of one of the most potent compounds. Limitations, including compound solubility and degradation at acidic pH, have prevented thorough investigation of the potential of these compounds. Our studies reveal the efficacious nature of the malononitrile moiety in targeting cNTnC and its potential in future cardiotonic drug design.
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Affiliation(s)
- Brittney A. Klein
- Department of Biochemistry, Faculty of Medicine and Dentistry, University of Alberta, Edmonton, Alberta T6G 2H7, Canada
| | - Ian M. Robertson
- Ministry of Health, Government of Alberta, Edmonton, Alberta T5J 1S6, Canada
| | - Béla Reiz
- Department of Chemistry, Faculty of Science, University of Alberta, Edmonton, Alberta T6G 2G2, Canada
| | - Thomas Kampourakis
- Randall Division of Cell and Molecular Biophysics, King’s College London, New Hunt’s House, London, SE1 1UL, U.K
| | - Liang Li
- Department of Chemistry, Faculty of Science, University of Alberta, Edmonton, Alberta T6G 2G2, Canada
| | - Brian D. Sykes
- Department of Biochemistry, Faculty of Medicine and Dentistry, University of Alberta, Edmonton, Alberta T6G 2H7, Canada
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Klein BA, Reiz B, Robertson IM, Irving M, Li L, Sun YB, Sykes BD. Reversible Covalent Reaction of Levosimendan with Cardiac Troponin C in Vitro and in Situ. Biochemistry 2018; 57:2256-2265. [DOI: 10.1021/acs.biochem.8b00109] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/17/2022]
Affiliation(s)
- Brittney A. Klein
- Department of Biochemistry, Faculty of Medicine and Dentistry, University of Alberta, Edmonton, Alberta T6G 2H7, Canada
| | - Béla Reiz
- Department of Chemistry, Faculty of Science, University of Alberta, Edmonton, Alberta T6H 2H7, Canada
| | - Ian M. Robertson
- Pharmaceutical and Health Benefits Branch, Ministry of Health, Government of Alberta, Edmonton, Alberta T5J 3Z5, Canada
| | - Malcolm Irving
- Randall Centre for Cell and Molecular Biophysics and British Heart Foundation Centre of Research Excellence, King’s College London, London SE1 1UL, U.K
| | - Liang Li
- Department of Chemistry, Faculty of Science, University of Alberta, Edmonton, Alberta T6H 2H7, Canada
| | - Yin-Biao Sun
- Randall Centre for Cell and Molecular Biophysics and British Heart Foundation Centre of Research Excellence, King’s College London, London SE1 1UL, U.K
| | - Brian D. Sykes
- Department of Biochemistry, Faculty of Medicine and Dentistry, University of Alberta, Edmonton, Alberta T6G 2H7, Canada
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Sung MM, Byrne NJ, Robertson IM, Kim TT, Samokhvalov V, Levasseur J, Soltys CL, Fung D, Tyreman N, Denou E, Jones KE, Seubert JM, Schertzer JD, Dyck JRB. Resveratrol improves exercise performance and skeletal muscle oxidative capacity in heart failure. Am J Physiol Heart Circ Physiol 2017; 312:H842-H853. [PMID: 28159807 DOI: 10.1152/ajpheart.00455.2016] [Citation(s) in RCA: 55] [Impact Index Per Article: 7.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/27/2016] [Revised: 01/18/2017] [Accepted: 01/30/2017] [Indexed: 12/19/2022]
Abstract
We investigated whether treatment of mice with established pressure overload-induced heart failure (HF) with the naturally occurring polyphenol resveratrol could improve functional symptoms of clinical HF such as fatigue and exercise intolerance. C57Bl/6N mice were subjected to either sham or transverse aortic constriction surgery to induce HF. Three weeks postsurgery, a cohort of mice with established HF (%ejection fraction <45) was administered resveratrol (~450 mg·kg-1·day-1) or vehicle for 2 wk. Although the percent ejection fraction was similar between both groups of HF mice, those mice treated with resveratrol had increased total physical activity levels and exercise capacity. Resveratrol treatment was associated with altered gut microbiota composition, increased skeletal muscle insulin sensitivity, a switch toward greater whole body glucose utilization, and increased basal metabolic rates. Although muscle mass and strength were not different between groups, mice with HF had significant declines in basal and ADP-stimulated O2 consumption in isolated skeletal muscle fibers compared with sham mice, which was completely normalized by resveratrol treatment. Overall, resveratrol treatment of mice with established HF enhances exercise performance, which is associated with alterations in whole body and skeletal muscle energy metabolism. Thus, our preclinical data suggest that resveratrol supplementation may effectively improve fatigue and exercise intolerance in HF patients.NEW & NOTEWORTHY Resveratrol treatment of mice with heart failure leads to enhanced exercise performance that is associated with altered gut microbiota composition, increased whole body glucose utilization, and enhanced skeletal muscle metabolism and function. Together, these preclinical data suggest that resveratrol supplementation may effectively improve fatigue and exercise intolerance in heart failure via these mechanisms.
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Affiliation(s)
- Miranda M Sung
- Faculty of Medicine and Dentistry, Department of Pediatrics, Cardiovascular Research Centre, Mazankowski Alberta Heart Institute, University of Alberta, Edmonton, Alberta, Canada
| | - Nikole J Byrne
- Faculty of Medicine and Dentistry, Department of Pediatrics, Cardiovascular Research Centre, Mazankowski Alberta Heart Institute, University of Alberta, Edmonton, Alberta, Canada
| | - Ian M Robertson
- Faculty of Medicine and Dentistry, Department of Pediatrics, Cardiovascular Research Centre, Mazankowski Alberta Heart Institute, University of Alberta, Edmonton, Alberta, Canada
| | - Ty T Kim
- Faculty of Medicine and Dentistry, Department of Pediatrics, Cardiovascular Research Centre, Mazankowski Alberta Heart Institute, University of Alberta, Edmonton, Alberta, Canada
| | - Victor Samokhvalov
- Faculty of Pharmacy & Pharmaceutical Sciences, Cardiovascular Research Centre, University of Alberta, Edmonton, Alberta, Canada
| | - Jody Levasseur
- Alberta Heart Failure Etiology and Analysis Research Team, Alberta Heritage Foundation for Medical Research Interdisciplinary Team Grant, Edmonton, Alberta, Canada
| | - Carrie-Lynn Soltys
- Faculty of Medicine and Dentistry, Department of Pediatrics, Cardiovascular Research Centre, Mazankowski Alberta Heart Institute, University of Alberta, Edmonton, Alberta, Canada
| | - David Fung
- Faculty of Medicine and Dentistry, Department of Pediatrics, Cardiovascular Research Centre, Mazankowski Alberta Heart Institute, University of Alberta, Edmonton, Alberta, Canada
| | - Neil Tyreman
- Department of Physical Education, University of Alberta, Edmonton, Alberta, Canada; and
| | - Emmanuel Denou
- Department of Biochemistry and Biomedical Sciences and Farncombe Family Digestive Health Research Institute, McMaster University, Hamilton, Ontario, Canada
| | - Kelvin E Jones
- Department of Physical Education, University of Alberta, Edmonton, Alberta, Canada; and
| | - John M Seubert
- Faculty of Pharmacy & Pharmaceutical Sciences, Cardiovascular Research Centre, University of Alberta, Edmonton, Alberta, Canada
| | - Jonathan D Schertzer
- Department of Biochemistry and Biomedical Sciences and Farncombe Family Digestive Health Research Institute, McMaster University, Hamilton, Ontario, Canada
| | - Jason R B Dyck
- Faculty of Medicine and Dentistry, Department of Pediatrics, Cardiovascular Research Centre, Mazankowski Alberta Heart Institute, University of Alberta, Edmonton, Alberta, Canada; .,Alberta Heart Failure Etiology and Analysis Research Team, Alberta Heritage Foundation for Medical Research Interdisciplinary Team Grant, Edmonton, Alberta, Canada
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7
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Matsumura N, Robertson IM, Hamza SM, Soltys CLM, Sung MM, Masson G, Beker DL, Dyck JRB. A novel complex I inhibitor protects against hypertension-induced left ventricular hypertrophy. Am J Physiol Heart Circ Physiol 2017; 312:H561-H570. [PMID: 28062414 DOI: 10.1152/ajpheart.00604.2016] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/05/2016] [Revised: 12/18/2016] [Accepted: 01/03/2017] [Indexed: 11/22/2022]
Abstract
Since left ventricular hypertrophy (LVH) increases the susceptibility for the development of other cardiac conditions, pharmacotherapy that mitigates pathological cardiac remodeling may prove to be beneficial in patients with LVH. Previous work has shown that the activation of the energy-sensing kinase AMP-activated protein kinase (AMPK) can inhibit some of the molecular mechanisms that are involved in LVH. Of interest, metformin activates AMPK through its inhibition of mitochondrial complex I in the electron transport chain and can prevent LVH induced by pressure overload. However, metformin has additional cellular effects unrelated to AMPK activation, raising questions about whether mitochondrial complex I inhibition is sufficient to reduce LVH. Herein, we characterize the cardiac effects of a novel compound (R118), which is a more potent complex I inhibitor than metformin and is thus used at a much lower concentration. We show that R118 activates AMPK in the cardiomyocyte, inhibits multiple signaling pathways involved in LVH, and prevents Gq protein-coupled receptor agonist-induced prohypertrophic signaling. We also show that in vivo administration of R118 prevents LVH in a mouse model of hypertension, suggesting that R118 can directly modulate the response of the cardiomyocyte to stress. Of importance, we also show that while R118 treatment prevents adaptive remodelling in response to elevated afterload, it does so without compromising systolic function, improves myocardial energetics, and prevents a decline in diastolic function in hypertensive mice. Taken together, our data suggest that inhibition of mitochondrial complex I may be worthy of future investigation for the treatment of LVH.NEW & NOTEWORTHY Inhibition of mitochondrial complex I by R118 reduces left ventricular hypertrophy (LVH) and improves myocardial energetics as well as diastolic function without compromising systolic function. Together, these effects demonstrate the therapeutic potential of complex I inhibitors in the treatment of LVH, even in the presence of persistent hypertension.
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Affiliation(s)
- Nobutoshi Matsumura
- Department of Pediatrics, Faculty of Medicine and Dentistry, Cardiovascular Research Centre, University of Alberta, Edmonton, Alberta, Canada
| | - Ian M Robertson
- Department of Pediatrics, Faculty of Medicine and Dentistry, Cardiovascular Research Centre, University of Alberta, Edmonton, Alberta, Canada
| | - Shereen M Hamza
- Department of Pediatrics, Faculty of Medicine and Dentistry, Cardiovascular Research Centre, University of Alberta, Edmonton, Alberta, Canada
| | - Carrie-Lynn M Soltys
- Department of Pediatrics, Faculty of Medicine and Dentistry, Cardiovascular Research Centre, University of Alberta, Edmonton, Alberta, Canada
| | - Miranda M Sung
- Department of Pediatrics, Faculty of Medicine and Dentistry, Cardiovascular Research Centre, University of Alberta, Edmonton, Alberta, Canada
| | - Grant Masson
- Department of Pediatrics, Faculty of Medicine and Dentistry, Cardiovascular Research Centre, University of Alberta, Edmonton, Alberta, Canada
| | - Donna L Beker
- Department of Pediatrics, Faculty of Medicine and Dentistry, Cardiovascular Research Centre, University of Alberta, Edmonton, Alberta, Canada
| | - Jason R B Dyck
- Department of Pediatrics, Faculty of Medicine and Dentistry, Cardiovascular Research Centre, University of Alberta, Edmonton, Alberta, Canada
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Robertson IM, Pineda-Sanabria SE, Yan Z, Kampourakis T, Sun YB, Sykes BD, Irving M. Reversible Covalent Binding to Cardiac Troponin C by the Ca2+-Sensitizer Levosimendan. Biochemistry 2016; 55:6032-6045. [DOI: 10.1021/acs.biochem.6b00758] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Affiliation(s)
- Ian M. Robertson
- Randall
Division of Cell and Molecular Biophysics and British Heart Foundation
Centre of Research Excellence, King’s College London, New Hunt’s
House, Guy’s Campus, London, SE1 1UL, U.K
- Department
of Biochemistry, Faculty of Medicine and Dentistry, University of Alberta, Edmonton, Alberta T6G 2H7, Canada
| | - Sandra E. Pineda-Sanabria
- Department
of Biochemistry, Faculty of Medicine and Dentistry, University of Alberta, Edmonton, Alberta T6G 2H7, Canada
| | - Ziqian Yan
- Randall
Division of Cell and Molecular Biophysics and British Heart Foundation
Centre of Research Excellence, King’s College London, New Hunt’s
House, Guy’s Campus, London, SE1 1UL, U.K
| | - Thomas Kampourakis
- Randall
Division of Cell and Molecular Biophysics and British Heart Foundation
Centre of Research Excellence, King’s College London, New Hunt’s
House, Guy’s Campus, London, SE1 1UL, U.K
| | - Yin-Biao Sun
- Randall
Division of Cell and Molecular Biophysics and British Heart Foundation
Centre of Research Excellence, King’s College London, New Hunt’s
House, Guy’s Campus, London, SE1 1UL, U.K
| | - Brian D. Sykes
- Department
of Biochemistry, Faculty of Medicine and Dentistry, University of Alberta, Edmonton, Alberta T6G 2H7, Canada
| | - Malcolm Irving
- Randall
Division of Cell and Molecular Biophysics and British Heart Foundation
Centre of Research Excellence, King’s College London, New Hunt’s
House, Guy’s Campus, London, SE1 1UL, U.K
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9
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Wang LL, Herwadkar A, Reich JM, Johnson DD, House SD, Peña-Martin P, Rockett AA, Robertson IM, Gupta S, Pecharsky VK. Towards Direct Synthesis of Alane: A Predicted Defect-Mediated Pathway Confirmed Experimentally. ChemSusChem 2016; 9:2358-2364. [PMID: 27535100 DOI: 10.1002/cssc.201600338] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/11/2016] [Revised: 06/13/2016] [Indexed: 06/06/2023]
Abstract
Alane (AlH3 ) is a unique energetic material that has not found a broad practical use for over 70 years because it is difficult to synthesize directly from its elements. Using density functional theory, we examine the defect-mediated formation of alane monomers on Al(111) in a two-step process: (1) dissociative adsorption of H2 and (2) alane formation, which are both endothermic on a clean surface. Only with Ti dopant to facilitate H2 dissociation and vacancies to provide Al adatoms, both processes become exothermic. In agreement, in situ scanning tunneling microscopy showed that during H2 exposure, alane monomers and clusters form primarily in the vicinity of Al vacancies and Ti atoms. Moreover, ball milling of the Al samples with Ti (providing necessary defects) showed a 10 % conversion of Al into AlH3 or closely related species at 344 bar H2 , indicating that the predicted pathway may lead to the direct synthesis of alane from elements at pressures much lower than the 10(4) bar expected from bulk thermodynamics.
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Affiliation(s)
- Lin-Lin Wang
- Ames Laboratory, U.S. Department of Energy, Ames, IA, 50011-3020, USA
| | - Aditi Herwadkar
- Ames Laboratory, U.S. Department of Energy, Ames, IA, 50011-3020, USA
| | - Jason M Reich
- Ames Laboratory, U.S. Department of Energy, Ames, IA, 50011-3020, USA
- Department of Chemistry, University of Illinois Urbana-Champaign, 505 South Mathews Ave., Urbana, IL, 61801, USA
| | - Duane D Johnson
- Ames Laboratory, U.S. Department of Energy, Ames, IA, 50011-3020, USA.
- Department of Materials Science & Engineering, Iowa State University, 2200H Hoover Hall, Ames, IA, 50011-2300, USA.
- Department of Materials Science & Engineering, University of Illinois Urbana-Champaign, 1304 W. Green St., Urbana, IL, 61801, USA.
| | - Stephen D House
- Department of Materials Science & Engineering, University of Illinois Urbana-Champaign, 1304 W. Green St., Urbana, IL, 61801, USA
- Department of Chemical and Petroleum Engineering, University of Pittsburgh, 3700 O'Hara St., Pittsburgh, PA, 15261, USA
| | - Pamela Peña-Martin
- Department of Materials Science & Engineering, University of Illinois Urbana-Champaign, 1304 W. Green St., Urbana, IL, 61801, USA
| | - Angus A Rockett
- Department of Materials Science & Engineering, University of Illinois Urbana-Champaign, 1304 W. Green St., Urbana, IL, 61801, USA
| | - Ian M Robertson
- Department of Materials Science & Engineering, University of Illinois Urbana-Champaign, 1304 W. Green St., Urbana, IL, 61801, USA
- Department of Materials Science & Engineering, University of Wisconsin-Madison, 1415 Engineering Dr., Madison, WI, 53706, USA
| | - Shalabh Gupta
- Ames Laboratory, U.S. Department of Energy, Ames, IA, 50011-3020, USA
| | - Vitalij K Pecharsky
- Ames Laboratory, U.S. Department of Energy, Ames, IA, 50011-3020, USA.
- Department of Materials Science & Engineering, Iowa State University, 2200H Hoover Hall, Ames, IA, 50011-2300, USA.
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11
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Pineda-Sanabria SE, Robertson IM, Sun YB, Irving M, Sykes BD. Probing the mechanism of cardiovascular drugs using a covalent levosimendan analog. J Mol Cell Cardiol 2016; 92:174-84. [PMID: 26853943 PMCID: PMC4831045 DOI: 10.1016/j.yjmcc.2016.02.003] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/01/2015] [Revised: 01/24/2016] [Accepted: 02/02/2016] [Indexed: 01/16/2023]
Abstract
One approach to improve contraction in the failing heart is the administration of calcium (Ca2 +) sensitizers. Although it is known that levosimendan and other sensitizers bind to troponin C (cTnC), their in vivo mechanism is not fully understood. Based on levosimendan, we designed a covalent Ca2 + sensitizer (i9) that targets C84 of cTnC and exchanged this complex into cardiac muscle. The NMR structure of the covalent complex showed that i9 binds deep in the hydrophobic pocket of cTnC. Despite slightly reducing troponin I affinity, i9 enhanced the Ca2 + sensitivity of cardiac muscle. We conclude that i9 enhances Ca2 + sensitivity by stabilizing the open conformation of cTnC. These findings provide new insights into the in vivo mechanism of Ca2 + sensitization and demonstrate that directly targeting cTnC has significant potential in cardiovascular therapy. A Ca2 + sensitizer, i9 was designed that forms a covalent bond with C84 of cTnC. i9 stabilized the open state of the N-domain of cTnC. The structure of the covalent cTnC-cTnI-i9 complex was solved by NMR. The structure showed that i9 binds deep in the hydrophobic pocket of cTnC. Despite slightly reducing cTnI affinity, i9 enhanced the Ca2 + sensitivity of cardiac muscle.
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Affiliation(s)
- Sandra E Pineda-Sanabria
- Department of Biochemistry, Faculty of Medicine & Dentistry, University of Alberta, Edmonton, AB T6G 2H7, Canada
| | - Ian M Robertson
- Randall Division of Cell and Molecular Biophysics and British Heart Foundation Centre of Research Excellence, New Hunt's House, Guy's Campus, King's College London, London SE1 1UL, UK
| | - Yin-Biao Sun
- Randall Division of Cell and Molecular Biophysics and British Heart Foundation Centre of Research Excellence, New Hunt's House, Guy's Campus, King's College London, London SE1 1UL, UK
| | - Malcolm Irving
- Randall Division of Cell and Molecular Biophysics and British Heart Foundation Centre of Research Excellence, New Hunt's House, Guy's Campus, King's College London, London SE1 1UL, UK
| | - Brian D Sykes
- Department of Biochemistry, Faculty of Medicine & Dentistry, University of Alberta, Edmonton, AB T6G 2H7, Canada.
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Elizabeth Pineda-Sanabria S, Robertson IM, Sun YB, Irving M, Sykes BD. Structure and Function of the Levosimendan Analog I9 Covalently Bound to Cardiac Troponin C. Biophys J 2016. [DOI: 10.1016/j.bpj.2015.11.712] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022] Open
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13
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Pineda-Sanabria SE, Robertson IM, Sykes BD. Structure and Dynamics of the Acidosis-Resistant A162H Mutant of the Switch Region of Troponin I Bound to the Regulatory Domain of Troponin C. Biochemistry 2015; 54:3583-93. [DOI: 10.1021/acs.biochem.5b00178] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/06/2023]
Affiliation(s)
- Sandra E. Pineda-Sanabria
- Department of Biochemistry, ‡Department of Pediatrics, Faculty of Medicine & Dentistry, University of Alberta, Edmonton, AB T6G 2H7, Canada
| | - Ian M. Robertson
- Department of Biochemistry, ‡Department of Pediatrics, Faculty of Medicine & Dentistry, University of Alberta, Edmonton, AB T6G 2H7, Canada
| | - Brian D. Sykes
- Department of Biochemistry, ‡Department of Pediatrics, Faculty of Medicine & Dentistry, University of Alberta, Edmonton, AB T6G 2H7, Canada
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Robertson IM, Pineda-Sanabria SE, Holmes PC, Sykes BD. Conformation of the critical pH sensitive region of troponin depends upon a single residue in troponin I. Arch Biochem Biophys 2014; 552-553:40-9. [DOI: 10.1016/j.abb.2013.12.003] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/14/2013] [Revised: 11/18/2013] [Accepted: 12/05/2013] [Indexed: 12/20/2022]
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15
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Robertson IM, Sevrieva I, Li MX, Irving M, Sun YB, Sykes BD. In Vitro and in Situ Structure and Function of the Cardiac Troponin C Familial Hypertrophic Cardiomyopathy-Linked Mutation, L29Q. Biophys J 2014. [DOI: 10.1016/j.bpj.2013.11.3996] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022] Open
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16
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Pineda-Sanabria SE, Robertson IM, Holmes PC, Sykes BD. The Histidine Button Dictates the Conformation of the pH-Sensitive Region of Troponin I. Biophys J 2014. [DOI: 10.1016/j.bpj.2013.11.2644] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022] Open
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17
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Pineda-Sanabria SE, Robertson IM, Li MX, Sykes BD. Interaction between the regulatory domain of cardiac troponin C and the acidosis-resistant cardiac troponin I A162H. Cardiovasc Res 2012. [DOI: 10.1093/cvr/cvs348] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
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18
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Wang D, Robertson IM, Li MX, McCully ME, Crane ML, Luo Z, Tu AY, Daggett V, Sykes BD, Regnier M. Structural and functional consequences of the cardiac troponin C L48Q Ca(2+)-sensitizing mutation. Biochemistry 2012; 51:4473-87. [PMID: 22591429 DOI: 10.1021/bi3003007] [Citation(s) in RCA: 34] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
Calcium binding to the regulatory domain of cardiac troponin C (cNTnC) causes a conformational change that exposes a hydrophobic surface to which troponin I (cTnI) binds, prompting a series of protein-protein interactions that culminate in muscle contraction. A number of cTnC variants that alter the Ca(2+) sensitivity of the thin filament have been linked to disease. Tikunova and Davis engineered a series of cNTnC mutations that altered Ca(2+) binding properties and studied the effects on the Ca(2+) sensitivity of the thin filament and contraction [Tikunova, S. B., and Davis, J. P. (2004) J. Biol. Chem. 279, 35341-35352]. One of the mutations they engineered, the L48Q variant, resulted in a pronounced increase in the cNTnC Ca(2+) binding affinity and Ca(2+) sensitivity of cardiac muscle force development. In this work, we sought structural and mechanistic explanations for the increased Ca(2+) sensitivity of contraction for the L48Q cNTnC variant, using an array of biophysical techniques. We found that the L48Q mutation enhanced binding of both Ca(2+) and cTnI to cTnC. Nuclear magnetic resonance chemical shift and relaxation data provided evidence that the cNTnC hydrophobic core is more exposed with the L48Q variant. Molecular dynamics simulations suggest that the mutation disrupts a network of crucial hydrophobic interactions so that the closed form of cNTnC is destabilized. The findings emphasize the importance of cNTnC's conformation in the regulation of contraction and suggest that mutations in cNTnC that alter myofilament Ca(2+) sensitivity can do so by modulating Ca(2+) and cTnI binding.
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Affiliation(s)
- Dan Wang
- Department of Bioengineering, University of Washington, Seattle, Washington 98195, United States
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19
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Pineda-Sanabria SE, Robertson IM, Li MX, Sykes BD. Structural Investigation of the Acidosis Resistant Cardiac Troponin I Mutant A162H. Biophys J 2012. [DOI: 10.1016/j.bpj.2011.11.3048] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022] Open
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20
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Robertson IM, Holmes PC, Li MX, Pineda-Sanabria SE, Baryshnikova OK, Sykes BD. Elucidation of isoform-dependent pH sensitivity of troponin i by NMR spectroscopy. J Biol Chem 2011; 287:4996-5007. [PMID: 22179777 DOI: 10.1074/jbc.m111.301499] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/17/2023] Open
Abstract
Myocardial ischemia is characterized by reduced blood flow to cardiomyocytes, which can lead to acidosis. Acidosis decreases the calcium sensitivity and contractile efficiency of cardiac muscle. By contrast, skeletal and neonatal muscles are much less sensitive to changes in pH. The pH sensitivity of cardiac muscle can be reduced by replacing cardiac troponin I with its skeletal or neonatal counterparts. The isoform-specific response of troponin I is dictated by a single histidine, which is replaced by an alanine in cardiac troponin I. The decreased pH sensitivity may stem from the protonation of this histidine at low pH, which would promote the formation of electrostatic interactions with negatively charged residues on troponin C. In this study, we measured acid dissociation constants of glutamate residues on troponin C and of histidine on skeletal troponin I (His-130). The results indicate that Glu-19 comes in close contact with an ionizable group that has a pK(a) of ∼6.7 when it is in complex with skeletal troponin I but not when it is bound to cardiac troponin I. The pK(a) of Glu-19 is decreased when troponin C is bound to skeletal troponin I and the pK(a) of His-130 is shifted upward. These results strongly suggest that these residues form an electrostatic interaction. Furthermore, we found that skeletal troponin I bound to troponin C tighter at pH 6.1 than at pH 7.5. The data presented here provide insights into the molecular mechanism for the pH sensitivity of different muscle types.
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Affiliation(s)
- Ian M Robertson
- Department of Biochemistry, Faculty of Medicine and Dentistry, University of Alberta, Edmonton, Alberta T6G 2H7, Canada
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21
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Robertson IM, Boyko RF, Sykes BD. Visualizing the principal component of ¹H, ¹⁵N-HSQC NMR spectral changes that reflect protein structural or functional properties: application to troponin C. J Biomol NMR 2011; 51:115-122. [PMID: 21947920 DOI: 10.1007/s10858-011-9546-9] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/11/2011] [Accepted: 07/13/2011] [Indexed: 05/31/2023]
Abstract
Laboratories often repeatedly determine the structure of a given protein under a variety of conditions, mutations, modifications, or in a number of states. This approach can be cumbersome and tedious. Given then a database of structures, identifiers, and corresponding (1)H,(15)N-HSQC NMR spectra for homologous proteins, we investigated whether structural information could be ascertained for a new homolog solely from its (1)H,(15)N-HSQC NMR spectrum. We addressed this question with two different approaches. First, we used a semi-automated approach with the program, ORBplus. ORBplus looks for patterns in the chemical shifts and correlates these commonalities to the explicit property of interest. ORBplus ranks resonances based on consistency of the magnitude and direction of the chemical shifts within the database, and the chemical shift correlation of the unknown protein with the database. ORBplus visualizes the results by a histogram and a vector diagram, and provides residue specific predictions on structural similarities with the database. The second method we used was partial least squares (PLS), which is a multivariate statistical technique used to correlate response and predictor variables. We investigated the ability of these methods to predict the tertiary structure of the contractile regulatory protein troponin C. Troponin C undergoes a closed-to-open conformational change, which is coupled to its function in muscle. We found that both ORBplus and PLS were able to identify patterns in the (1)H,(15)N-HSQC NMR data from different states of troponin C that correlated to its conformation.
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Affiliation(s)
- Ian M Robertson
- Department of Biochemistry, University of Alberta, Edmonton, AB T5K 2W7, Canada
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22
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Barron JN, Christie RV, Fraser DB, Garrod LP, Mansfield OT, Morgan HV, Mowlem R, Robertson IM, Roxburgh AC, Roxburgh IA, Christie RV, Garrod LP. REPORT ON THERAPEUTIC PROPERTIES OF PENICILLIN: I. A Penicillin Therapeutic Research Unit. Br Med J 2011; 1:513-4. [PMID: 20785376 DOI: 10.1136/bmj.1.4345.513] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/04/2022]
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Abstract
AbstractRecrystallization and grain growth studies of Al-Mg-Mn-Zr alloys have been carried out in-situ in the transmission electron microscope. Nucleation sites were primarily on large (>I μm diameter) eutectic constituent particles. The sub-micron A16Mn dispersoids were observed to be effective as nuclei if present in clusters, and were effective at retarding grain boundary migration and dislocation motion. The smaller A13Zr precipitates seemed to have little effect on nucleation and growth, but were effective in pinning dislocations. These results have been analyzed in terms of precipitate size and shape in both the as-cold-worked microstructure and during recrystallization. The implications on the microstructural refinement of these alloys for improved superplastic properties will be discussed.
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Wei H, Wang Z, Zhang J, House S, Gao YG, Yang L, Robinson H, Tan LH, Xing H, Hou C, Robertson IM, Zuo JM, Lu Y. Time-dependent, protein-directed growth of gold nanoparticles within a single crystal of lysozyme. Nat Nanotechnol 2011; 6:93-97. [PMID: 21278750 DOI: 10.1038/nnano.2010.280] [Citation(s) in RCA: 116] [Impact Index Per Article: 8.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/04/2010] [Accepted: 12/13/2010] [Indexed: 05/30/2023]
Abstract
Gold nanoparticles are useful in biomedical applications due to their distinct optical properties and high chemical stability. Reports of the biogenic formation of gold colloids from gold complexes has also led to an increased level of interest in the biomineralization of gold. However, the mechanism responsible for biomolecule-directed gold nanoparticle formation remains unclear due to the lack of structural information about biological systems and the fast kinetics of biomimetic chemical systems in solution. Here we show that intact single crystals of lysozyme can be used to study the time-dependent, protein-directed growth of gold nanoparticles. The protein crystals slow down the growth of the gold nanoparticles, allowing detailed kinetic studies to be carried out, and permit a three-dimensional structural characterization that would be difficult to achieve in solution. Furthermore, we show that additional chemical species can be used to fine-tune the growth rate of the gold nanoparticles.
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Affiliation(s)
- Hui Wei
- Department of Chemistry, University of Illinois at Urbana-Champaign, Urbana, Illinois 61801, USA
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25
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Szeto SS, Robertson IM, Sun YB, Sykes BD. Orientation of the Calcium Sensitizing Agent dfbp-o, when Bound to Troponin in a Muscle Fiber as Determined by Solid-State NMR Spectroscopy. Biophys J 2011. [DOI: 10.1016/j.bpj.2010.12.3381] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/18/2022] Open
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26
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Pineda-Sanabria SE, Robertson IM, Sykes BD. Structure of trans-resveratrol in complex with the cardiac regulatory protein troponin C. Biochemistry 2011; 50:1309-20. [PMID: 21226534 DOI: 10.1021/bi101985j] [Citation(s) in RCA: 31] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/17/2022]
Abstract
Cardiac troponin, a heterotrimeric protein complex that regulates heart contraction, represents an attractive target for the development of drugs for treating heart disease. Cardiovascular diseases are one of the chief causes of morbidity and mortality worldwide. In France, however, the death rate from heart disease is remarkably low relative to fat consumption. This so-called "French paradox" has been attributed to the high level of consumption of wine in France, and the antioxidant trans-resveratrol is thought to be the primary basis for wine's cardioprotective nature. It has been demonstrated that trans-resveratrol increases the myofilament Ca(2+) sensitivity of guinea pig myocytes [Liew, R., Stagg, M. A., MacLeod, K. T., and Collins, P. (2005) Eur. J. Pharmacol. 519, 1-8]; however, the specific mode of its action is unknown. In this study, the structure of trans-resveratrol free and bound to the calcium-binding protein, troponin C, was determined by nuclear magnetic resonance spectroscopy. The results indicate that trans-resveratrol undergoes a minor conformational change upon binding to the hydrophobic pocket of the C-domain of troponin C. The location occupied by trans-resveratrol coincides with the binding site of troponin I, troponin C's natural binding partner. This has been seen for other troponin C-targeting inotropes and implicates the modulation of the troponin C-troponin I interaction as a possible mechanism of action for trans-resveratrol.
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Affiliation(s)
- Sandra E Pineda-Sanabria
- Department of Biochemistry, Faculty of Medicine and Dentistry, University of Alberta, Edmonton, Alberta, Canada
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27
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Jacobs BW, Houk RJT, Anstey MR, House SD, Robertson IM, Talin AA, Allendorf MD. Ordered metal nanostructureself-assembly using metal–organic frameworks as templates. Chem Sci 2011. [DOI: 10.1039/c0sc00377h] [Citation(s) in RCA: 59] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022] Open
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28
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Robertson IM, Sun YB, Li MX, Sykes BD. A structural and functional perspective into the mechanism of Ca2+-sensitizers that target the cardiac troponin complex. J Mol Cell Cardiol 2010; 49:1031-41. [PMID: 20801130 DOI: 10.1016/j.yjmcc.2010.08.019] [Citation(s) in RCA: 52] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/13/2010] [Revised: 08/17/2010] [Accepted: 08/19/2010] [Indexed: 11/25/2022]
Abstract
The Ca(2+) dependent interaction between troponin I (cTnI) and troponin C (cTnC) triggers contraction in heart muscle. Heart failure is characterized by a decrease in cardiac output, and compounds that increase the sensitivity of cardiac muscle to Ca(2+) have therapeutic potential. The Ca(2+)-sensitizer, levosimendan, targets cTnC; however, detailed understanding of its mechanism has been obscured by its instability. In order to understand how this class of positive inotropes function, we investigated the mode of action of two fluorine containing novel analogs of levosimendan; 2',4'-difluoro(1,1'-biphenyl)-4-yloxy acetic acid (dfbp-o) and 2',4'-difluoro(1,1'-biphenyl)-4-yl acetic acid (dfbp). The affinities of dfbp and dfbp-o for the regulatory domain of cTnC were measured in the absence and presence of cTnI by NMR spectroscopy, and dfbp-o was found to bind more strongly than dfbp. Dfbp-o also increased the affinity of cTnI for cTnC. Dfbp-o increased the Ca(2+)-sensitivity of demembranated cardiac trabeculae in a manner similar to levosimendan. The high resolution NMR solution structure of the cTnC-cTnI-dfbp-o ternary complex showed that dfbp-o bound at the hydrophobic interface formed by cTnC and cTnI making critical interactions with residues such as Arg147 of cTnI. In the absence of cTnI, docking localized dfbp-o to the same position in the hydrophobic groove of cTnC. The structural and functional data reveal that the levosimendan class of Ca(2+)-sensitizers work by binding to the regulatory domain of cTnC and stabilizing the pivotal cTnC-cTnI regulatory unit via a network of hydrophobic and electrostatic interactions, in contrast to the destabilizing effects of antagonists such as W7 at the same interface.
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Affiliation(s)
- Ian M Robertson
- Department of Biochemistry, University of Alberta, Edmonton, Alberta, Canada
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29
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Dadfarnia M, Novak P, Ahn DC, Liu JB, Sofronis P, Johnson DD, Robertson IM. Recent advances in the study of structural materials compatibility with hydrogen. Adv Mater 2010; 22:1128-1135. [PMID: 20217854 DOI: 10.1002/adma.200904354] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/28/2023]
Abstract
Hydrogen is a ubiquitous element that enters materials from many different sources. It almost always has a deleterious effect on mechanical properties. In non-hydride-forming systems, research to date has identified hydrogen-enhanced localized plasticity and hydrogen-induced decohesion as two viable mechanisms for embrittlement. However, a fracture prediction methodology that associates macroscopic parameters with the degradation mechanisms at the microscale has not been established, as of yet. In this article, we report recent work on modeling and simulation of hydrogen-induced crack initiation and growth. Our goal is to develop methodologies to relate characteristics of the degradation mechanisms from microscopic observations and first-principles calculations with macroscopic indices of embrittlement. The approach we use involves finite element analysis of the coupled hydrogen transport problem with hydrogen-assisted elastoplastic deformation, thermodynamic theories of decohesion, and ab initio density functional theory calculations of the hydrogen effect on grain boundaries.
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Affiliation(s)
- M Dadfarnia
- Department of Mechanical Science and Engineering University of Illinois at Urbana-Champaign 1206 West Green Street, Urbana, IL 61801, USA
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Brewer LN, Follstaedt DM, Hattar K, Knapp JA, Rodriguez MA, Robertson IM. Competitive abnormal grain growth between allotropic phases in nanocrystalline nickel. Adv Mater 2010; 22:1161-1164. [PMID: 20401941 DOI: 10.1002/adma.200904245] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/29/2023]
Affiliation(s)
- L N Brewer
- Sandia National Laboratories Albuquerque, NM 87185, USA.
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Oleszczuk M, Robertson IM, Li MX, Sykes BD. Solution structure of the regulatory domain of human cardiac troponin C in complex with the switch region of cardiac troponin I and W7: the basis of W7 as an inhibitor of cardiac muscle contraction. J Mol Cell Cardiol 2010; 48:925-33. [PMID: 20116385 DOI: 10.1016/j.yjmcc.2010.01.016] [Citation(s) in RCA: 26] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/21/2009] [Revised: 01/19/2010] [Accepted: 01/20/2010] [Indexed: 10/19/2022]
Abstract
The solution structure of Ca(2+)-bound regulatory domain of cardiac troponin C (cNTnC) in complex with the switch region of troponin I (cTnI(147-163)) and the calmodulin antagonist, N-(6-aminohexyl)-5-chloro-1-naphthalenesulfinamide (W7), has been determined by NMR spectroscopy. The structure reveals that the W7 naphthalene ring interacts with the terminal methyl groups of M47, M60, and M81 as well as aliphatic and aromatic side chains of several other residues in the hydrophobic pocket of cNTnC. The H3 ring proton of W7 also contacts the methyl groups of I148 and M153 of cTnI(147-163). The N-(6-aminohexyl) tail interacts primarily with the methyl groups of V64 and M81, which are located on the C- and D-helices of cNTnC. Compared to the structure of the cNTnC*Ca(2+)*W7 complex (Hoffman, R. M. B. and Sykes, B. D. (2009) Biochemistry 48, 5541-5552), the tail of W7 reorients slightly toward the surface of cNTnC while the ring remains in the hydrophobic pocket. The positively charged -NH(3)(+) group from the tail of W7 repels the positively charged R147 of cTnI(147-163). As a result, the N-terminus of the peptide moves away from cNTnC and the helical content of cTnI(147-163) is diminished, when compared to the structure of cNTnC*Ca(2+)*cTnI(147-163) (Li, M. X., Spyracopoulos, L., and Sykes B. D. (1999) Biochemistry 38, 8289-8298). Thus the ternary structure cNTnC*Ca(2+)*W7*cTnI(147-163) reported in this study offers an explanation for the approximately 13-fold affinity reduction of cTnI(147-163) for cNTnC*Ca(2+) in the presence of W7 and provides a structural basis for the inhibitory effect of W7 in cardiac muscle contraction. This generates molecular insight into structural features that are useful for the design of cTnC-specific Ca(2+)-desensitizing drugs.
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Affiliation(s)
- Marta Oleszczuk
- Department of Biochemistry, School of Molecular and Systems Medicine, University of Alberta, Edmonton, Alberta, Canada T6G 2H7
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Robertson IM, Li MX, Boyko RF, Crane ML, Regnier M, Sykes BD. The Perturbation of the Open-Closed Transition of Troponin C by the Mutation L48Q Leads to an Enhanced Troponin I Affinity. Biophys J 2010. [DOI: 10.1016/j.bpj.2009.12.804] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/19/2022] Open
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33
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Oleszczuk M, Robertson IM, Li MX, Sykes BD. Structure of the Regulatory Domain of Human Cardiac Troponin C in Complex with the Switch Region of Cardiac Troponin I and the Drug W7: The Basis of W7 as an Inhibitor of Cardiac Muscle Contraction. Biophys J 2010. [DOI: 10.1016/j.bpj.2009.12.806] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/19/2022] Open
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34
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Houk RJT, Jacobs BW, El Gabaly F, Chang NN, Talin AA, Graham DD, House SD, Robertson IM, Allendorf MD. Silver cluster formation, dynamics, and chemistry in metal-organic frameworks. Nano Lett 2009; 9:3413-3418. [PMID: 19757817 DOI: 10.1021/nl901397k] [Citation(s) in RCA: 139] [Impact Index Per Article: 9.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/28/2023]
Abstract
Synthetic methods used to produce metal nanoparticles typically lead to a distribution of particle sizes. In addition, creation of the smallest clusters, with sizes of a few to tens of atoms, remains very challenging. Nanoporous metal-organic frameworks (MOFs) are a promising solution to these problems, since their long-range crystalline order creates completely uniform pore sizes with the potential for both steric and chemical stabilization. We report a systematic investigation of silver nanocluster formation within MOFs using three representative MOF templates. The as-synthesized clusters are spectroscopically consistent with dimensions < or =1 nm, with a significant fraction existing as Ag(3) clusters, as shown by electron paramagnetic resonance. Importantly, we show conclusively that very rapid TEM-induced MOF degradation leads to agglomeration and stable, easily imaged particles, explaining prior reports of particles larger than MOF pores. These results solve an important riddle concerning MOF-based templates and suggest that heterostructures composed of highly uniform arrays of nanoparticles within MOFs are feasible.
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Affiliation(s)
- Ronald J T Houk
- Sandia National Laboratories, Livermore, California 94551-0969, USA
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Robertson IM, Li MX, Sykes BD. Solution structure of human cardiac troponin C in complex with the green tea polyphenol, (-)-epigallocatechin 3-gallate. J Biol Chem 2009; 284:23012-23. [PMID: 19542563 DOI: 10.1074/jbc.m109.021352] [Citation(s) in RCA: 51] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/28/2023] Open
Abstract
Heart muscle contraction is regulated by Ca(2+) binding to the thin filament protein troponin C. In cardiovascular disease, the myofilament response to Ca(2+) is often altered. Compounds that rectify this perturbation are of considerable interest as therapeutics. Plant flavonoids have been found to provide protection against a variety of human illnesses such as cancer, infection, and heart disease. (-)-Epigallocatechin gallate (EGCg), the prevalent flavonoid in green tea, modulates force generation in isolated guinea pig hearts (Hotta, Y., Huang, L., Muto, T., Yajima, M., Miyazeki, K., Ishikawa, N., Fukuzawa, Y., Wakida, Y., Tushima, H., Ando, H., and Nonogaki, T. (2006) Eur. J. Pharmacol. 552, 123-130) and in skinned cardiac muscle fibers (Liou, Y. M., Kuo, S. C., and Hsieh, S. R. (2008) Pflugers Arch. 456, 787-800; and Tadano, N., Yumoto, F., Tanokura, M., Ohtsuki, I., and Morimoto, S. (2005) Biophys. J. 88, 314a). In this study we describe the solution structure of the Ca(2+)-saturated C-terminal domain of troponin C in complex with EGCg. Moreover, we show that EGCg forms a ternary complex with the C-terminal domain of troponin C and the anchoring region of troponin I. The structural evidence indicates that the binding site of EGCg on the C-terminal domain of troponin C is in the hydrophobic pocket in the absence of troponin I, akin to EMD 57033. Based on chemical shift mapping, the binding of EGCg to the C-terminal domain of troponin C in the presence of troponin I may be to a new site formed by the troponin C.troponin I complex. This interaction of EGCg with the C-terminal domain of troponin C.troponin I complex has not been shown with other cardiotonic molecules and illustrates the potential mechanism by which EGCg modulates heart contraction.
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Affiliation(s)
- Ian M Robertson
- Department of Biochemistry, University of Alberta, Edmonton, Alberta T6G 2H7, Canada
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Matsukawa Y, Briceno M, Robertson IM. Combining in situ transmission electron microscopy and molecular dynamics computer simulations to reveal the interaction mechanisms of dislocations with stacking-fault tetrahedron in nuclear materials. Microsc Res Tech 2009; 72:284-92. [PMID: 19189314 DOI: 10.1002/jemt.20681] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022]
Abstract
In situ straining experiments conducted in a transmission electron microscope have been performed to reveal how dislocations interact with and annihilate isolated stacking-fault tetrahedra, common defect clusters in irradiated face-centered cubic metals. Comparison of the experimental results with the predictions from molecular dynamics computer simulations shows some similarities and some striking differences. The comparison suggests challenges for the simulations and demonstrates how, despite the disparity in operational parameters, the simulations can be used to interpret experimental results.
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Affiliation(s)
- Yoshitaka Matsukawa
- Department of Materials Science & Engineering, University of Illinois, Urbana, Illinois 61801, USA.
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Robertson IM, Spyracopoulos L, Sykes BD. The Evaluation of Isotope Editing and Filtering for Protein—Ligand Interaction Elucidation by Nmr. NATO Science for Peace and Security Series B: Physics and Biophysics 2009. [DOI: 10.1007/978-90-481-2368-1_7] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/23/2022]
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Baryshnikova OK, Robertson IM, Mercier P, Sykes BD. The Dilated Cardiomyopathy G159D Mutation in Cardiac Troponin C Weakens the Anchoring Interaction with Troponin I. Biochemistry 2008; 47:10950-60. [DOI: 10.1021/bi801165c] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Affiliation(s)
- Olga K. Baryshnikova
- Department of Biochemistry, University of Alberta, Edmonton, Alberta, Canada T6G 2H7
| | - Ian M. Robertson
- Department of Biochemistry, University of Alberta, Edmonton, Alberta, Canada T6G 2H7
| | - Pascal Mercier
- Department of Biochemistry, University of Alberta, Edmonton, Alberta, Canada T6G 2H7
| | - Brian D. Sykes
- Department of Biochemistry, University of Alberta, Edmonton, Alberta, Canada T6G 2H7
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Robertson IM, Baryshnikova OK, Li MX, Sykes BD. Defining the binding site of levosimendan and its analogues in a regulatory cardiac troponin C-troponin I complex. Biochemistry 2008; 47:7485-95. [PMID: 18570382 PMCID: PMC2652250 DOI: 10.1021/bi800438k] [Citation(s) in RCA: 28] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
The interaction of Cardiac Troponin C (cTnC) and Cardiac Troponin I (cTnI) plays a critical role in transmitting the Ca (2+) signal to the other myofilament proteins in the activation of cardiac muscle contraction. As such, the cTnC-cTnI interface is a logical target for cardiotonic agents such as levosimendan that can modulate the Ca (2+) sensitivity of the myofilaments. Evidence indicates that drug candidates may exert their effects by targeting a site formed by binding of the switch region of cTnI to the regulatory N domain of cTnC (cNTnC). In this study, we utilized two-dimensional (1)H- (15)N HSQC NMR spectroscopy to monitor the binding of levosimendan and its analogues, CMDP, AMDP, CI-930, imazodan, and MPDP, to cNTnC.Ca (2+) in complex with two versions of the switch region of cTnI (cTnI 147-163 and cTnI 144-163). Levosimendan, CMDP, AMDP, and CI-930 were found to bind to both cNTnC.Ca (2+).cTnI 147-163 and cNTnC.Ca (2+).cTnI 144-163 complexes. These compounds contain a methyl group that is absent in MPDP or imazodan. Thus, the methyl group is one of the pharmacophores responsible for the action of these pyridazinone drugs on cTnC. Furthermore, the results showed that the cNTnC.Ca (2+).cTnI 144-163 complex presents a higher-affinity binding site for these compounds than the cNTnC.Ca (2+).cTnI 147-163 complex. This is consistent with our observation that the affinity of cTnI 144-163 for cNTnC.Ca (2+) is approximately 10-fold stronger than that of cTnI 147-163, likely a result of electrostatic forces between the N-terminal RRV extension in cTnI 144-163 and the acidic residues in the C and D helices of cNTnC. These results will help in the delineation of the mode of action of levosimendan on the important functional unit of cardiac troponin that constitutes the regulatory domain of cTnC and the switch region of cTnI.
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Affiliation(s)
- Ian M Robertson
- Department of Biochemistry, University of Alberta, Edmonton, Alberta, Canada T6G 2H7
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Li MX, Robertson IM, Sykes BD. Interaction of cardiac troponin with cardiotonic drugs: a structural perspective. Biochem Biophys Res Commun 2007; 369:88-99. [PMID: 18162171 DOI: 10.1016/j.bbrc.2007.12.108] [Citation(s) in RCA: 32] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/02/2007] [Accepted: 12/11/2007] [Indexed: 11/29/2022]
Abstract
Over the 40 years since its discovery, many studies have focused on understanding the role of troponin as a myofilament based molecular switch in regulating the Ca(2+)-dependent activation of striated muscle contraction. Recently, studies have explored the role of cardiac troponin as a target for cardiotonic agents. These drugs are clinically useful for treating heart failure, a condition in which the heart is no longer able to pump enough blood to other organs. These agents act via a mechanism that modulates the Ca(2+)-sensitivity of troponin; such a mode of action is therapeutically desirable because intracellular Ca(2+) concentration is not perturbed, preserving the regulation of other Ca(2+)-based signaling pathways. This review describes molecular details of the interaction of cardiac troponin with a variety of cardiotonic drugs. We present recent structural work that has identified the docking sites of several cardiotonic drugs in the troponin C-troponin I interface and discuss their relevance in the design of troponin based drugs for the treatment of heart disease.
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Affiliation(s)
- Monica X Li
- Department of Biochemistry, University of Alberta, Edmonton, Alta., Canada
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Affiliation(s)
- I M Robertson
- The Chemistry Department, Edinburgh and East of Scotland College of Agriculture
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Li CM, Robertson IM, Jenkins ML, Hutchison JL, Doole RC. In situ TEM observation of the nucleation and growth of silver oxide nanoparticles. Micron 2005; 36:9-15. [PMID: 15582473 DOI: 10.1016/j.micron.2004.07.001] [Citation(s) in RCA: 17] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/22/2003] [Revised: 05/20/2004] [Accepted: 07/23/2004] [Indexed: 11/29/2022]
Abstract
The nucleation, growth, and coalescence of silver oxide nanoparticles have been investigated dynamically and at high spatial resolution by using the electron beam of a transmission electron microscope to stimulate and to observe the processes. Under the assumption the particles are hemispherical, the growth rate was found to be proportional to the square root of the electron irradiation time. This result suggests that the rate-limiting step is the attachment of atoms to the nanoparticles. Growth of the nanoparticles occurred by the addition of columns of atoms on {111} planes. Particle impingement resulted in interpenetration of the particles and, ultimately, the formation of a grain boundary.
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Affiliation(s)
- Chun-Ming Li
- Department of Materials Science and Engineering, University of Illinois at Urbana-Champaign, 1304 W. Green Street, Urbana, IL 61801, USA
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Abstract
Anetoderma in premature infants is an uncommon lesion that may be associated with the use of various types of monitoring leads. In 2 infants multiple papules of anetoderma occurred on the forehead in association with the use of gel electrocardiographic electrodes. It is postulated that the cause of these papules was a local hypoxemia caused by pressure from the electrodes. Growth-restricted infants may be particularly predisposed to iatrogenic anetoderma.
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Affiliation(s)
- P B Colditz
- Perinatal Research Centre, Royal Women's Hospital, University of Queensland, Brisbane, Australia
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Abstract
A 31-year-old female is described who developed benign hypergammaglobulinaemic purpura and lymphoid interstitial pneumonitis concomitantly. High titre anti-nuclear antibodies were also noted. Several years previously, the patient had developed myasthenia gravis and multiple sclerosis. The present case is an example of multiple medical disorders characterized by immune dysregulation and represents the first reported associated of hypergammaglobulinaemic purpura with lymphoid interstitial pneumonitis.
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Affiliation(s)
- R M Miller
- Department of Dermatology, Royal Brisbane Hospital, Queensland, Australia
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Abstract
The design of a controlled environment electron microscope is described and examples are presented to demonstrate the information that can be obtained by studying gas-solid interactions in real time and at high spatial resolution.
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Affiliation(s)
- I M Robertson
- Department of Materials Science and Engineering, University of Illinois, Urbana 61801, USA
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Abstract
BACKGROUND Acquired ichthyosis (AI) has been described in a variety of clinical situations. We have observed cases of ichthyosis in bone marrow transplant recipients. OBJECTIVE Our purpose was to characterize these changes clinically and histologically and to compare them with other cases of acquired ichthyosis. METHODS Skin biopsy specimens were taken before transplantation and from affected areas after transplantation. RESULTS AI was observed in four patients who had received a bone marrow transplant for leukemia. None of the patients had a previous personal or family history of ichthyosis. In all patients graft-versus-host disease developed after transplantation. The eruption clinically and histologically most closely resembled ichthyosis vulgaris. The ichthyotic changes appeared to be unrelated to specific drug therapy. CONCLUSION AI is a previously unreported cutaneous complication of bone marrow transplantation. It may be related to graft-versus-host disease in these patients.
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Affiliation(s)
- L J Spelman
- Department of Dermatology, Royal Brisbane Hospital, Australia
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Tappin DK, Robertson IM, Birnbaum HK. Enhancement of the electron-irradiation-induced amorphization of Zr2Ni and Zr3Al by hydrogen. Phys Rev B Condens Matter 1995; 51:14854-14860. [PMID: 9978436 DOI: 10.1103/physrevb.51.14854] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 04/12/2023]
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Abstract
Bone marrow transplantation is associated with numerous cutaneous complications that may be related to the underlying (preexisting) disease, to pretransplant conditioning, to immunosuppression, to concomitant medication, or to graft-versus-host reaction. We describe four bone marrow transplant recipients with the clinical and histologic features of pityriasis rosea, a hitherto unreported association.
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Affiliation(s)
- L J Spelman
- Department of Dermatology, Royal Brisbane Hospital, Australia
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Robertson IM. Electron microscopy of interfaces in metals and alloys, by C.T. Forwood and L.M. Clarebrough. Adam Hilger, Bristol, UK, 1991, 424 pp, $150.00. Microsc Res Tech 1993. [DOI: 10.1002/jemt.1070240611] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
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