1
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Yu B, Wang X, Ding L, Han M, Guo Y. Hydrophilic Natural Polylysine as Drug Nanocarrier for Preparation of Helical Delivery System. Pharmaceutics 2022; 14:pharmaceutics14112512. [PMID: 36432704 PMCID: PMC9696163 DOI: 10.3390/pharmaceutics14112512] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/19/2022] [Revised: 11/15/2022] [Accepted: 11/15/2022] [Indexed: 11/22/2022] Open
Abstract
Polypeptide materials have clear secondary structure and biodegradability, which can be further modified and functionalized, so that they can be employed as therapeutic agents in clinical applications. PEGylation of polylysine (PEG-PLL) is a kind of safe and effective nanocarrier that is utilized for gene and drug delivery. However, PEG-PLL needs to be produced through chemical synthesis, which is expensive and difficult to obtain. We hope to simplify the nanocarrier and use hydrophilic natural polylysine (PLL) to develop a high-efficacy delivery system. To evaluate the possibility of PLL as nanocarriers, methotrexate (MTX) is selected as a model drug and PEG-PLL is utilized as control nanocarriers. The experimental results showed that PLL is an ideal polypeptide to prepare MTX-loaded PLL nanoparticles (PLL/MTX NPs). Compared with PEG-PLL as nanocarriers, PLL/MTX NPs showed higher drug-loading content (58.9%) and smaller particle sizes (113.7 nm). Moreover, the shape of PLL/MTX NPs was a unique helical nanorod. The PLL/MTX NPs had good storage stability, media stability, and sustained release effect. Animal research demonstrated that PLL/MTX NPs could improve the anti-tumor activity of MTX, the antitumor efficacy is enhanced 1.9-fold and 1.2-fold compared with MTX injection and PEG-PLL/MTX NPs, respectively. To sum up, natural polymer PLL is an ideal nano drug delivery carrier which has potential clinical applications.
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Affiliation(s)
- Bo Yu
- Institute of Medicinal Plant Development, Chinese Academy of Medical Sciences & Peking Union Medical College, No. 151, Malianwa North Road, Haidian District, Beijing 100193, China
| | - Xiangtao Wang
- Institute of Medicinal Plant Development, Chinese Academy of Medical Sciences & Peking Union Medical College, No. 151, Malianwa North Road, Haidian District, Beijing 100193, China
| | - Lijuan Ding
- Institute of Medicinal Plant Development, Chinese Academy of Medical Sciences & Peking Union Medical College, No. 151, Malianwa North Road, Haidian District, Beijing 100193, China
| | - Meihua Han
- Institute of Medicinal Plant Development, Chinese Academy of Medical Sciences & Peking Union Medical College, No. 151, Malianwa North Road, Haidian District, Beijing 100193, China
| | - Yifei Guo
- Institute of Medicinal Plant Development, Chinese Academy of Medical Sciences & Peking Union Medical College, No. 151, Malianwa North Road, Haidian District, Beijing 100193, China
- Key Laboratory of Bioactive Substances and Resources Utilization of Chinese Herbal Medicine, Ministry of Education, Chinese Academy of Medical Sciences & Peking Union Medical College, Beijing 100193, China
- Key Laboratory of New Drug Discovery Based on Classic Chinese Medicine Prescription, Chinese Academy of Medical Sciences, No. 151, Malianwa North Road, Haidian District, Beijing 100193, China
- Beijing Key Laboratory of Innovative Drug Discovery of Traditional Chinese Medicine (Natural Medicine) and Translational Medicine, No. 151, Malianwa North Road, Haidian District, Beijing 100193, China
- Correspondence:
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2
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Ferenczy GG, Kellermayer M. Contribution of Hydrophobic Interactions to Protein Mechanical Stability. Comput Struct Biotechnol J 2022; 20:1946-1956. [PMID: 35521554 PMCID: PMC9062142 DOI: 10.1016/j.csbj.2022.04.025] [Citation(s) in RCA: 12] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/25/2021] [Revised: 04/07/2022] [Accepted: 04/17/2022] [Indexed: 11/26/2022] Open
Abstract
The role of hydrophobic and polar interactions in providing thermodynamic stability to folded proteins has been intensively studied, but the relative contribution of these interactions to the mechanical stability is less explored. We used steered molecular dynamics simulations with constant-velocity pulling to generate force-extension curves of selected protein domains and monitor hydrophobic surface unravelling upon extension. Hydrophobic contribution was found to vary between one fifth and one third of the total force while the rest of the contribution is attributed primarily to hydrogen bonds. Moreover, hydrophobic force peaks were shifted towards larger protein extensions with respect to the force peaks attributed to hydrogen bonds. The higher importance of hydrogen bonds compared to hydrophobic interactions in providing mechanical resistance is in contrast with the relative importance of the hydrophobic interactions in providing thermodynamic stability of proteins. The different contributions of these interactions to the mechanical stability are explained by the steeper free energy dependence of hydrogen bonds compared to hydrophobic interactions on the relative positions of interacting atoms. Comparative analyses for several protein domains revealed that the variation of hydrophobic forces is modest, while the contribution of hydrogen bonds to the force peaks becomes increasingly important for mechanically resistant protein domains.
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3
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Wu B, Hanay SB, Kimmins SD, Cryan SA, Hermida Merino D, Heise A. Ion-Triggered Hydrogels Self-Assembled from Statistical Copolypeptides. ACS Macro Lett 2022; 11:323-328. [PMID: 35575374 PMCID: PMC8928472 DOI: 10.1021/acsmacrolett.1c00774] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/06/2023]
Abstract
![]()
Statistical copolypeptides
comprising lysine and tyrosine with
unprecedented ion-induced gelation behavior are reported. Copolypeptides
are obtained by one-step N-carboxyanhydride (NCA)
ring-opening polymerization. The gelation mechanism is studied by
in situ SAXS analyses, in addition to optical spectroscopy and transmission
electron microscopy (TEM). It is found that the gelation of these
statistically polymerized polypeptides is due to the formation of
stable intermolecular β-sheet secondary structures induced by
the presence of salt ions as well as the aggregation of an α-helix
between the copolypeptides. This behavior is unique to the statistical
lysine/tyrosine copolypeptides and was not observed in any other amino
acid combination or arrangement. Furthermore, the diffusion and mechanical
properties of these hydrogels can be tuned through tailoring the polypeptide
chain length and ion strength.
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Affiliation(s)
- Bing Wu
- Department of Chemistry, RCSI University of Medicine and Health Sciences, Dublin 2, Ireland
- Dutch-Belgian Beamline (DUBBLE), ESRF - The European Synchrotron Radiation Facility, CS 40220, Grenoble 38043 Cedex 9, France
| | - Saltuk B. Hanay
- Department of Chemistry, RCSI University of Medicine and Health Sciences, Dublin 2, Ireland
| | - Scott D. Kimmins
- Instituto de Química, Pontificia Universidad Católica de Valparaíso, Avda. Universidad 330, Curauma, Placilla 2950, Valparaíso, Chile
| | - Sally-Ann Cryan
- School of Pharmacy and Biomolecular Sciences and Tissue Engineering Research Group, RCSI University of Medicine and Health Sciences, Dublin 2, Ireland
- Science Foundation Ireland (SFI) Centre for Research in Medical Devices (CURAM), RCSI, Dublin 2, Ireland
- AMBER, The SFI Advanced Materials and Bioengineering Research Centre, RCSI, Dublin 2, Ireland
| | - Daniel Hermida Merino
- Dutch-Belgian Beamline (DUBBLE), ESRF - The European Synchrotron Radiation Facility, CS 40220, Grenoble 38043 Cedex 9, France
| | - Andreas Heise
- Department of Chemistry, RCSI University of Medicine and Health Sciences, Dublin 2, Ireland
- Science Foundation Ireland (SFI) Centre for Research in Medical Devices (CURAM), RCSI, Dublin 2, Ireland
- AMBER, The SFI Advanced Materials and Bioengineering Research Centre, RCSI, Dublin 2, Ireland
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4
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Deleray AC, Kramer JR. Biomimetic Glycosylated Polythreonines by N-Carboxyanhydride Polymerization. Biomacromolecules 2022; 23:1453-1461. [PMID: 35104406 DOI: 10.1021/acs.biomac.2c00020] [Citation(s) in RCA: 6] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
Glycosylated threonine (Thr) is a structural motif found in seemingly disparate natural proteins from deep-sea collagen to mucins. Synthetic mimics of these important proteins are of great interest in biomedicine. Such materials also provide ready access to probe the contributions of individual amino acids to protein structure in a controlled and tunable manner. N-Carboxyanhydride (NCA) polymerization is one major route to such biomimetic polypeptides. However, challenges in the preparation and polymerization of Thr NCAs have impeded obtaining such structures. Here, we present optimized routes to several glycosylated and acetylated Thr NCAs of high analytical purity. Transition metal catalysis produced tunable homo-, statistical, and block-polypeptides with predictable chain lengths and low dispersities. We conducted structural work to examine their aqueous conformations and found that a high content of free OH Thr induces the formation of water-insoluble β-sheets. However, glycosylation appears to induce a polyproline II-type helical conformation, which sheds light on the role of glyco-Thr in rigid proteins such as mucins and collagen.
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Affiliation(s)
- Anna C Deleray
- Department of Biomedical Engineering, University of Utah, Salt Lake City, Utah 84112, United States
| | - Jessica R Kramer
- Department of Biomedical Engineering, University of Utah, Salt Lake City, Utah 84112, United States
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5
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Klemm P, Behnke M, Solomun JI, Bonduelle C, Lecommandoux S, Traeger A, Schubert S. Self-assembled PEGylated amphiphilic polypeptides for gene transfection. J Mater Chem B 2021; 9:8224-8236. [PMID: 34643200 DOI: 10.1039/d1tb01495a] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/02/2023]
Abstract
In the present study, three biodegradable block copolymers composed of a poly(ethylene glycol) block and a copolypeptide block with varying compositions of cationic L-lysine (L-Lys) and hydrophobic benzyl-L-glutamate (Bzl-L-Glu) were designed for gene delivery applications. The polypeptides were synthesized by ring opening polymerization (ROP) and after orthogonal deprotection of Boc-L-Lys side chains, the polymer exhibited an amphiphilic character. To bind or encapsulate plasmid DNA (pDNA), different formulations were investigated: a nanoprecipitation and an emulsion technique using various organic solvents as well as an aqueous pH-controlled formulation method. The complex and nanoparticle (NP) formations were monitored by dynamic light scattering (DLS), and pDNA interaction was shown by gel electrophoresis and subsequent controlled release with heparin. The polypeptides were further tested for their cytotoxicity as well as biodegradability. The complexes and NPs presenting the most promising size distributions and pDNA binding ability were subsequently evaluated for their transfection efficiency in HEK293T cells. The highest transfection efficiencies were obtained with an aqueous formulation of the polypeptide containing the highest L-Lys content and lowest proportion of hydrophobic, helical structures (P1*), which is therefore a promising candidate for efficient gene delivery by biodegradable gene delivery vectors.
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Affiliation(s)
- Paul Klemm
- Laboratory of Organic and Macromolecular Chemistry (IOMC), Friedrich Schiller University Jena, Humboldtstrasse 10, 07743 Jena, Germany.,Jena Center for Soft Matter (JCSM), Friedrich Schiller University Jena, Philosophenweg 7, 07743 Jena, Germany.
| | - Mira Behnke
- Laboratory of Organic and Macromolecular Chemistry (IOMC), Friedrich Schiller University Jena, Humboldtstrasse 10, 07743 Jena, Germany.,Jena Center for Soft Matter (JCSM), Friedrich Schiller University Jena, Philosophenweg 7, 07743 Jena, Germany.
| | - Jana I Solomun
- Laboratory of Organic and Macromolecular Chemistry (IOMC), Friedrich Schiller University Jena, Humboldtstrasse 10, 07743 Jena, Germany.,Jena Center for Soft Matter (JCSM), Friedrich Schiller University Jena, Philosophenweg 7, 07743 Jena, Germany.
| | - Colin Bonduelle
- Univ. Bordeaux, CNRS, Bordeaux INP, LCPO, UMR 5629, F-33600, Pessac, France
| | | | - Anja Traeger
- Laboratory of Organic and Macromolecular Chemistry (IOMC), Friedrich Schiller University Jena, Humboldtstrasse 10, 07743 Jena, Germany.,Jena Center for Soft Matter (JCSM), Friedrich Schiller University Jena, Philosophenweg 7, 07743 Jena, Germany.
| | - Stephanie Schubert
- Jena Center for Soft Matter (JCSM), Friedrich Schiller University Jena, Philosophenweg 7, 07743 Jena, Germany. .,Institute of Pharmacy, Department of Pharmaceutical Technology and Biopharmacy, Friedrich Schiller University Jena, Lessingstrasse 8, 07743 Jena, Germany
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6
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Batys P, Morga M, Bonarek P, Sammalkorpi M. pH-Induced Changes in Polypeptide Conformation: Force-Field Comparison with Experimental Validation. J Phys Chem B 2020; 124:2961-2972. [PMID: 32182068 PMCID: PMC7590956 DOI: 10.1021/acs.jpcb.0c01475] [Citation(s) in RCA: 17] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/20/2020] [Indexed: 12/17/2022]
Abstract
Microsecond-long all-atom molecular dynamics (MD) simulations, circular dichroism, laser Doppler velocimetry, and dynamic light-scattering techniques have been used to investigate pH-induced changes in the secondary structure, charge, and conformation of poly l-lysine (PLL) and poly l-glutamic acid (PGA). The employed combination of the experimental methods reveals for both PLL and PGA a narrow pH range at which they are charged enough to form stable colloidal suspensions, maintaining their α-helix content above 60%; an elevated charge state of the peptides required for colloidal stability promotes the peptide solvation as a random coil. To obtain a more microscopic view on the conformations and to verify the modeling performance, peptide secondary structure and conformations rising in MD simulations are also examined using three different force fields, i.e., OPLS-AA, CHARMM27, and AMBER99SB*-ILDNP. Ramachandran plots reveal that in the examined setup the α-helix content is systematically overestimated in CHARMM27, while OPLS-AA overestimates the β-sheet fraction at lower ionization degrees. At high ionization degrees, the OPLS-AA force-field-predicted secondary structure fractions match the experimentally measured distribution most closely. However, the pH-induced changes in PLL and PGA secondary structure are reasonably captured only by the AMBER99SB*-ILDNP force field, with the exception of the fully charged PGA in which the α-helix content is overestimated. The comparison to simulations results shows that the examined force fields involve significant deviations in their predictions for charged homopolypeptides. The detailed mapping of secondary structure dependency on pH for the polypeptides, especially finding the stable colloidal α-helical regime for both examined peptides, has significant potential for practical applications of the charged homopolypeptides. The findings raise attention especially to the pH fine tuning as an underappreciated control factor in surface modification and self-assembly.
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Affiliation(s)
- Piotr Batys
- Jerzy
Haber Institute of Catalysis and Surface Chemistry, Polish Academy of Sciences, Niezapominajek 8, PL-30239 Krakow, Poland
| | - Maria Morga
- Jerzy
Haber Institute of Catalysis and Surface Chemistry, Polish Academy of Sciences, Niezapominajek 8, PL-30239 Krakow, Poland
| | - Piotr Bonarek
- Department
of Physical Biochemistry, Faculty of Biochemistry, Biophysics and
Biotechnology, Jagiellonian University, Krakow, Poland
| | - Maria Sammalkorpi
- Department of Chemistry and Materials Science and Department of Bioproducts and Biosystems, Aalto University, P.O. Box 16100, 00076 Aalto, Finland
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7
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Biocompatible antimicrobial electrospun nanofibers functionalized with ε-poly-l-lysine. Int J Pharm 2018; 553:141-148. [DOI: 10.1016/j.ijpharm.2018.10.037] [Citation(s) in RCA: 25] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/30/2018] [Revised: 10/11/2018] [Accepted: 10/15/2018] [Indexed: 01/23/2023]
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8
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Murphy RD, in het Panhuis M, Cryan SA, Heise A. Disulphide crosslinked star block copolypeptide hydrogels: influence of block sequence order on hydrogel properties. Polym Chem 2018. [DOI: 10.1039/c8py00741a] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
Strong redox responsive hydrogels with mechanical properties depending on the positioning of oligo(cysteine) within the star polypeptides were obtained.
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Affiliation(s)
- Robert D. Murphy
- Department of Chemistry
- Royal College of Surgeons in Ireland
- Dublin 2
- Ireland
| | - Marc in het Panhuis
- Soft Materials Group
- School of Chemistry
- and Australian Research Council Centre of Excellence for Electromaterials Science
- University of Wollongong
- Wollongong
| | - Sally-Ann Cryan
- Drug Delivery & Advanced Materials Team
- School of Pharmacy
- RCSI
- Dublin
- Ireland
| | - Andreas Heise
- Department of Chemistry
- Royal College of Surgeons in Ireland
- Dublin 2
- Ireland
- Centre for Research in Medical Devices (CURAM)
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9
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Patel M, Kaneko T, Matsumura K. Switchable release nano-reservoirs for co-delivery of drugs via a facile micelle–hydrogel composite. J Mater Chem B 2017; 5:3488-3497. [DOI: 10.1039/c7tb00701a] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/23/2022]
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10
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Jack C, Karimullah AS, Leyman R, Tullius R, Rotello VM, Cooke G, Gadegaard N, Barron LD, Kadodwala M. Biomacromolecular Stereostructure Mediates Mode Hybridization in Chiral Plasmonic Nanostructures. NANO LETTERS 2016; 16:5806-14. [PMID: 27547978 DOI: 10.1021/acs.nanolett.6b02549] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/28/2023]
Abstract
The refractive index sensitivity of plasmonic fields has been exploited for over 20 years in analytical technologies. While this sensitivity can be used to achieve attomole detection levels, they are in essence binary measurements that sense the presence/absence of a predetermined analyte. Using plasmonic fields, not to sense effective refractive indices but to provide more "granular" information about the structural characteristics of a medium, provides a more information rich output, which affords opportunities to create new powerful and flexible sensing technologies not limited by the need to synthesize chemical recognition elements. Here we report a new plasmonic phenomenon that is sensitive to the biomacromolecular structure without relying on measuring effective refractive indices. Chiral biomaterials mediate the hybridization of electric and magnetic modes of a chiral solid-inverse plasmonic structure, resulting in a measurable change in both reflectivity and chiroptical properties. The phenomenon originates from the electric-dipole-magnetic-dipole response of the biomaterial and is hence sensitive to biomacromolecular secondary structure providing unique fingerprints of α-helical, β-sheet, and disordered motifs. The phenomenon can be observed for subchiral plasmonic fields (i.e., fields with a lower chiral asymmetry than circularly polarized light) hence lifting constraints to engineer structures that produce fields with enhanced chirality, thus providing greater flexibility in nanostructure design. To demonstrate the efficacy of the phenomenon, we have detected and characterized picogram quantities of simple model helical biopolymers and more complex real proteins.
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Affiliation(s)
- Calum Jack
- School of Chemistry, Joseph Black Building, University of Glasgow , Glasgow G12 8QQ, United Kingdom
| | - Affar S Karimullah
- School of Chemistry, Joseph Black Building, University of Glasgow , Glasgow G12 8QQ, United Kingdom
- School of Engineering, Rankine Building, University of Glasgow , Glasgow G12 8LT, United Kingdom
| | - Ross Leyman
- School of Chemistry, Joseph Black Building, University of Glasgow , Glasgow G12 8QQ, United Kingdom
| | - Ryan Tullius
- School of Chemistry, Joseph Black Building, University of Glasgow , Glasgow G12 8QQ, United Kingdom
| | - Vincent M Rotello
- Department of Chemistry, 710 N. Pleasant Street, University of Massachusetts , Amherst, Massachusetts 01003, United States
| | - Graeme Cooke
- School of Chemistry, Joseph Black Building, University of Glasgow , Glasgow G12 8QQ, United Kingdom
| | - Nikolaj Gadegaard
- School of Engineering, Rankine Building, University of Glasgow , Glasgow G12 8LT, United Kingdom
| | - Laurence D Barron
- School of Chemistry, Joseph Black Building, University of Glasgow , Glasgow G12 8QQ, United Kingdom
| | - Malcolm Kadodwala
- School of Chemistry, Joseph Black Building, University of Glasgow , Glasgow G12 8QQ, United Kingdom
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11
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Sankaranarayanan K, Meenakshisundaram N. Micro-viscosity induced conformational transitions in poly-l-lysine. RSC Adv 2016. [DOI: 10.1039/c6ra11626d] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022] Open
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12
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Effect of peptide secondary structure on adsorption and adsorbed film properties on end-grafted polyethylene oxide layers. Acta Biomater 2014; 10:56-66. [PMID: 24060880 DOI: 10.1016/j.actbio.2013.09.010] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/13/2013] [Revised: 08/09/2013] [Accepted: 09/13/2013] [Indexed: 01/12/2023]
Abstract
Poly-l-lysine (PLL), in α-helix or β-sheet configuration, was used as a model peptide for investigating the effect of secondary structures on adsorption events to poly(ethylene oxide) (PEO) modified surfaces formed using θ solvents. Circular dichroism results showed that the secondary structure of PLL persisted upon adsorption to Au and PEO modified Au surfaces. Quartz crystal microbalance with dissipation (QCM-D) was used to characterize the chemisorbed PEO layer in different solvents (θ and good solvents), as well as the sequential adsorption of PLL in different secondary structures (α-helix or β-sheet). QCM-D results suggest that chemisorption of PEO 750 and 2000 from θ solutions led to brushes 3.8 ± 0.1 and 4.5 ± 0.1 nm thick with layer viscosities of 9.2 ± 0.8 and 4.8 ± 0.5 cP, respectively. The average number of H2O per ethylene oxides, while in θ solvent, was determined as ~0.9 and ~1.2 for the PEO 750 and 2000 layers, respectively. Upon immersion in good solvent (as used for PLL adsorption experiments), the number of H2O per ethylene oxides increased to ~1.5 and ~2.0 for PEO 750 and 2000 films, respectively. PLL adsorbed masses for α-helix and β-sheet on Au sensors was 231 ± 5 and 1087 ± 14 ng cm(-2), with layer viscosities of 2.3 ± 0.1 and 1.2 ± 0.1 cP, respectively; suggesting that the α-helix layer was more rigid, despite a smaller adsorbed mass, than that of β-sheet layers. The PEO 750 layer reduced PLL adsorbed amounts to ~10 and 12% of that on Au for α-helices and β-sheets respectively. The PLL adsorbed mass to PEO 2000 layers dropped to ~12% and 4% of that on Au, for α-helix and β-sheet respectively. No significant differences existed for the viscosities of adsorbed α-helix and β-sheet PLL on PEO surfaces. These results provide new insights into the fundamental understanding of the effects of secondary structures of peptides and proteins on their surface adsorption.
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13
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Binazadeh M, Faghihnejad A, Unsworth LD, Zeng H. Understanding the Effect of Secondary Structure on Molecular Interactions of Poly-l-lysine with Different Substrates by SFA. Biomacromolecules 2013; 14:3498-508. [DOI: 10.1021/bm400837t] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/07/2023]
Affiliation(s)
- Mojtaba Binazadeh
- Department of Chemical
and Materials Engineering, University of Alberta, Edmonton, Alberta, T6G 2V4, Canada
| | - Ali Faghihnejad
- Department of Chemical
and Materials Engineering, University of Alberta, Edmonton, Alberta, T6G 2V4, Canada
| | - Larry D. Unsworth
- Department of Chemical
and Materials Engineering, University of Alberta, Edmonton, Alberta, T6G 2V4, Canada
- National Institute of Nanotechnology, Edmonton, Alberta, T6G 2M9, Canada
| | - Hongbo Zeng
- Department of Chemical
and Materials Engineering, University of Alberta, Edmonton, Alberta, T6G 2V4, Canada
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14
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Effect of peptide secondary structure on adsorption and adsorbed film properties. Acta Biomater 2013; 9:6403-13. [PMID: 23376129 DOI: 10.1016/j.actbio.2013.01.018] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/24/2012] [Revised: 01/07/2013] [Accepted: 01/12/2013] [Indexed: 01/15/2023]
Abstract
Protein adsorption at the biomaterial-tissue interface is of utmost importance to the widespread application of engineered materials. The present study asked what role the secondary structures of peptides play in their adsorption, as well as how these structures affect the physicochemical properties of the final adsorbed layer. To this end, α-helices and β-sheets were induced in poly-l-lysine, and their adsorption to Au surfaces was monitored using quartz crystal microbalance with dissipation. It was observed that secondary structures played an important role in governing both the adsorption process and the final film properties. Higher initial adsorption rates were obtained for α-helices compared with β-sheets, regardless of solution salt concentration. Adsorption half-time for β-sheets was greater than that for α-helices, and the final amount adsorbed on β-sheet was significantly higher than that on α-helix. The adsorbed amount and adsorption half-time decreased with increasing salt concentration, suggesting that electrostatic interactions played a role. It was found that the differences in Zeta potential coupled with the apparent effect of surface contact area differences between α-helix and β-sheet conformations are ultimately responsible for these different peptide adsorption behaviours at the Au interface. The initial adsorption rate of α-helix increased with salt concentrations up to 50mM, whereas β-sheet initial adsorption rates increased with salt concentrations up to 500 mM. Viscosities for films formed from α-helices were about twice those of β-sheets films, regardless of solution ionic strength. It was evident that the peptide secondary structures influence all aspects of their adsorption, as well as affecting the adsorbed film properties.
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15
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Miserez A, Guerette PA. Phase transition-induced elasticity of α-helical bioelastomeric fibres and networks. Chem Soc Rev 2013; 42:1973-95. [DOI: 10.1039/c2cs35294j] [Citation(s) in RCA: 46] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
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16
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Binazadeh M, Kabiri M, Unsworth LD. Poly(ethylene glycol) and Poly(carboxy betaine) Based Nonfouling Architectures: Review and Current Efforts. ACS SYMPOSIUM SERIES 2012. [DOI: 10.1021/bk-2012-1120.ch028] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/17/2023]
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17
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Miserez A, Wasko SS, Carpenter CF, Waite JH. Non-entropic and reversible long-range deformation of an encapsulating bioelastomer. NATURE MATERIALS 2009; 8:910-916. [PMID: 19838185 DOI: 10.1038/nmat2547] [Citation(s) in RCA: 53] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/09/2009] [Accepted: 09/15/2009] [Indexed: 05/28/2023]
Abstract
Encapsulation is a widespread biological process particularly in the formation of protective egg cases of oviparous animals. The egg capsule wall of the channelled whelk Busycon canaliculum is an effective shock absorber with high reversible extensibility and a stiffness that changes significantly during extension. Here we show that post-stretch recovery in egg capsules is not driven by entropic forces as it is in rubber. Indeed, at fixed strain, force decreases linearly with increasing temperature, whereas in rubber elasticity the force increases. Instead, capsule wall recovery is associated with the internal energy arising from the facile and reversible structural alpha-helix <--> beta-sheet transition of egg capsule proteins during extension. This behaviour is extraordinary in the magnitude of energy dissipated and speed of recovery and is reminiscent of strain-induced crystallization in some polymeric fibres and of superelastic deformations associated with diffusionless phase transitions in shape-memory alloys.
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Affiliation(s)
- Ali Miserez
- Marine Science Institute, University of California, Santa Barbara, California 93106, USA.
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18
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Dzwolak W, Smirnovas V. A conformational α-helix to β-sheet transition accompanies racemic self-assembly of polylysine: an FT-IR spectroscopic study. Biophys Chem 2005; 115:49-54. [PMID: 15848283 DOI: 10.1016/j.bpc.2005.01.003] [Citation(s) in RCA: 41] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/11/2004] [Revised: 12/31/2004] [Accepted: 01/06/2005] [Indexed: 11/29/2022]
Abstract
The self-assembly of polylysine chains with opposite chiral senses is an intriguing phenomenon, suggesting that subtle hydrational effects may be a driving force of protein aggregation. We have used FT-IR spectroscopy to characterize the alpha-helix-to-beta-sheet conformational transition that accompanies the aggregation of single and mixed enantiomers of polylysine. The preferential racemic self-assembly not only takes place at a lower temperature, but is also less prone to repulsive electrostatic interactions between lysine charged side chains, caused by decreasing pH (pD). While the process is generally irreversible, it yet appears to proceed in a stepwise manner through a sequence of thermodynamically, rather than kinetically controlled events involving gradual destabilization of alpha-helices. Interestingly, although the alpha/beta-transition is in either case (single or mixed enantiomers) an endothermic process, it may also be induced by freezing of water, which leads to markedly more complete (and irreversible) aggregation of the mixed enantiomers. Relevance of these findings has been discussed in the context of protein aggregation studies.
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Affiliation(s)
- Wojciech Dzwolak
- Institute of High Pressure Physics, Polish Academy of Sciences, Warsaw.
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Dzwolak W, Ravindra R, Nicolini C, Jansen R, Winter R. The diastereomeric assembly of polylysine is the low-volume pathway for preferential formation of beta-sheet aggregates. J Am Chem Soc 2004; 126:3762-8. [PMID: 15038729 DOI: 10.1021/ja039138i] [Citation(s) in RCA: 69] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
The interaction of left- and right-handed polylysine chains (poly(D-lysine) and poly(L-lysine)) results in a dramatic increase in the propensity to form aggregated beta-sheet structure (and amyloid-like fibrils), which is reflected by an approximately 15 degrees C decrease of temperature of the alpha-helix-to-beta-sheet transition. While a relative volume expansion of 13-19 mL x mol(-1) accompanies the alpha-to-beta-transition in a single enantiomer, this does not hold true for the mixture, which, along with substantially more negative heat capacity changes, points to a lower solvent-entropy cost of the transition as the possible thermodynamic driving force of the diastereomeric aggregation. The underlying solvational mechanism may be one of the decisive factors responsible for the spontaneous protein aggregation in vivo and, as such, may shed new light on the molecular basis of amyloid-associated diseases.
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Affiliation(s)
- Wojciech Dzwolak
- High Pressure Research Center, Polish Academy of Sciences, Sokolowska 29/37, 01-142 Warsaw, Poland.
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Ohashi I, Pohoreki R, Morita K, Stemmer PM. Alcohols increase calmodulin affinity for Ca2+ and decrease target affinity for calmodulin. BIOCHIMICA ET BIOPHYSICA ACTA-MOLECULAR CELL RESEARCH 2004; 1691:161-7. [PMID: 15110996 DOI: 10.1016/j.bbamcr.2004.02.001] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/04/2003] [Revised: 02/04/2004] [Accepted: 02/06/2004] [Indexed: 11/29/2022]
Abstract
It has been proposed that alcohols and anesthetics selectively inhibit proteins containing easily disrupted motifs, e.g., alpha-helices. In this study, the calcineurin/calmodulin/Ca(2+) enzyme system was used to examine the effects of alcohols on calmodulin, a protein with a predominantly alpha-helical structure. Calcineurin phosphatase activity and Ca(2+) binding were monitored as indicators of calmodulin function. Alcohols inhibited enzyme activity in a concentration-dependent manner, with two-, four- and five-carbon n-alcohols exhibiting similar leftward shifts in the inhibition curves for calmodulin-dependent and -independent activities; the former was slightly more sensitive than the latter. Ca(2+) binding was measured by flow dialysis as a direct measure of calmodulin function, whereas, with the addition of a binding domain peptide, measured calmodulin-target interactions. Ethanol increased the affinity of calmodulin for Ca(2+) in the presence and absence of the peptide, indicating that ethanol stabilizes the Ca(2+) bound form of calmodulin. An increase in Ca(2+) affinity was detected in a calmodulin binding assay, but the affinity of calmodulin for calcineurin decreased at saturating Ca(2+). These data demonstrate that although specific regions within proteins may be more sensitive to alcohols and anesthetics, the presence of alpha-helices is unlikely to be a reliable indicator of alcohol or anesthetic potency.
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Affiliation(s)
- Ichiro Ohashi
- Department of Anesthesiology and Resuscitology, Okayama University Medical School, Okayama, Japan
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Dzwolak W, Muraki T, Kato M, Taniguchi Y. Chain-length dependence of ?-helix to ?-sheet transition in polylysine: Model of protein aggregation studied by temperature-tuned FTIR spectroscopy. Biopolymers 2004; 73:463-9. [PMID: 14991664 DOI: 10.1002/bip.10582] [Citation(s) in RCA: 64] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022]
Abstract
The chain-length dependence of the alpha-helix to beta-sheet transition in poly(L-lysine) is studied by temperature-tuned FTIR spectroscopy. This study shows that heterogeneous samples of poly(L-lysine), comprising polypeptide chains with various lengths, undergo the alpha-beta transition at an intermediate temperature compared to homogeneous ingredients. This holds true as long as each individual fraction of the polypeptide is capable of adopting an antiparallel beta-sheet structure. The tendency is that the longer chain is, the lower the alpha-beta transition temperature is, which has been linked to the presence of distorted or solvated helices with turns or beta sheets in elongating chains of poly(L-lysine). As such helical structures are apparently conducive to the alpha-beta transition, this draws a comparison to the hypothesis of metastable protein conformational states being a common stage in amyloid-formation pathways. The antiparallel architecture of the beta sheet is likely to reflect the pretransition interhelical interactions in poly(L-lysine). Namely, the chains are arranged in an antiparallel manner because of energetically favored antiparallel pre-assembly of dipolar alpha helices.
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Affiliation(s)
- Wojciech Dzwolak
- High Pressure Research Center, Polish Academy of Sciences, Sokolowska 29/37, 01-142 Warsaw, Poland
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Dzwolak W, Ravindra R, Winter R. Hydration and structure—the two sides of the insulin aggregation process. Phys Chem Chem Phys 2004. [DOI: 10.1039/b314086e] [Citation(s) in RCA: 38] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
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Dzwolak W, Ravindra R, Lendermann J, Winter R. Aggregation of bovine insulin probed by DSC/PPC calorimetry and FTIR spectroscopy. Biochemistry 2003; 42:11347-55. [PMID: 14503885 DOI: 10.1021/bi034879h] [Citation(s) in RCA: 150] [Impact Index Per Article: 7.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
Pressure perturbation calorimetry (PPC), differential scanning calorimetry (DSC), and time-resolved Fourier transform infrared spectroscopy (FTIR) have been employed to investigate aggregation of bovine insulin at pH 1.9. The aggregation process exhibits two distinguished phases. In the first phase, an intermediate molten globule-like conformational state is transiently formed, reflected by loose tertiary contacts and a robust H/D-exchange. This is followed by unfolding of the native secondary structure. The unfolding of insulin is fast, endothermic, partly reversible, and accompanied by a volume expansion of approximately 0.2%. The second phase consists of actual aggregation: an exothermic irreversible process revealing typical features of nucleation-controlled kinetics. The volumetric changes associated with the second phase are small. The concentration-dependence of DSC scans does not support a monomer intermediate model. While insulin aggregation under ambient pressure is fast and quantitative, pressure as low as 300 bar is sufficient to prevent the aggregation completely, as high-pressure FTIR spectroscopy revealed. This is explained in terms of the high pressure having an adverse effect on the thermal unfolding of insulin, and therefore preventing occurrence of the aggregation-prone intermediate. A comparison of the aggregation in H(2)O and D(2)O shows that the isotopic substitution has diverse effects on both the phases of aggregation. In heavy water, a more pronounced volume expansion accompanies the unfolding stage, while only the second phase shifts to higher temperature.
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Affiliation(s)
- Wojciech Dzwolak
- High-Pressure Research Center, Polish Academy of Sciences, Sokolowska 29/37, 01-142 Warsaw, Poland
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Gattoni M, Boffi A. The effect of isoflurane on erythrocyte membranes studied by ATR-FTIR. BIOCHIMICA ET BIOPHYSICA ACTA 2003; 1613:72-8. [PMID: 12832088 DOI: 10.1016/s0005-2736(03)00139-1] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
The effect of isoflurane on erythrocyte membranes has been investigated by means of attenuated total reflection infrared spectroscopy. Infrared spectra were measured on sonicated erythrocyte ghosts layered upon a ZnSe crystal covered with D(2)O saline solutions containing increasing amounts of isoflurane. At clinically relevant anesthetic concentrations and 37 degrees C, significant changes in the structural and dynamic properties of the membrane phospholipid bilayers are observed. Both the acyl chain methylene symmetric and asymmetric stretching modes and the carbonyl ester stretching band displayed frequency shifts interpreted as transitions toward disordered liquid-like structure accompanied by dehydration of the phospholipid polar heads. In turn, no secondary structure-linked changes are observed in the amide I region of membrane proteins. Higher anesthetic concentrations (500-900 microM), resulted in progressive detachment of the multilayers from the ATR crystal and irreversible formation of denatured protein. Polarization studies in correspondence of the acyl lipid methylene stretching bands indicated that isoflurane decreases the dichroic ratio thus inducing disorder in the orientation of the lipid acyl chains.
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Affiliation(s)
- Maurizio Gattoni
- Department of Biochemical Sciences, CNR Centro di Biologia Molecolare, University La Sapienza, P. Aldo Moro 5, 00185 Rome, Italy
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Acharya P, Segall ML, Zaiou M, Morrow J, Weisgraber KH, Phillips MC, Lund-Katz S, Snow J. Comparison of the stabilities and unfolding pathways of human apolipoprotein E isoforms by differential scanning calorimetry and circular dichroism. BIOCHIMICA ET BIOPHYSICA ACTA 2002; 1584:9-19. [PMID: 12213488 DOI: 10.1016/s1388-1981(02)00263-9] [Citation(s) in RCA: 60] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/24/2022]
Abstract
Differential scanning calorimetry and circular dichroism experiments were performed to study structural differences among the common isoforms of human apolipoprotein E (apoE2, apoE3, and apoE4) and their N-terminal, 22-kDa fragments. Here, we examine thermodynamic properties that characterize the structural differences among isoforms, and also differences in their unfolding behavior. The 22-kDa fragments and their full-length counterparts were found to exhibit similar differences in thermal stability (apoE4<apoE3<apoE2; T(max) approximately 52<56<59 degrees C, respectively). Helical contents at the onset and completion of denaturation (as monitored calorimetrically) were about 51% and 35%, respectively, for 22-kDa apoE3. As much as 70% of the unfolding enthalpy for 22-kDa apoE3 could be due to disruption of alpha-helix. The monomeric 22-kDa fragments unfold differently, with both apoE3 and apoE4 exhibiting unfolding intermediates, whereas apoE2 unfolds according to a two-state mechanism. Interactions with the C-terminal domain appear to destabilize the N-terminal domains in full-length apoE2 and apoE3, but less so for full-length apoE4. Self-association of full-length apoE at higher concentrations (1.5-2.5 mg/ml), as well as interaction of full-length apoE with phospholipid, enhances thermal stability. Cooperative changes in secondary structure, as monitored by circular dichroism, begin near 37 degrees C for full-length apoE3 and apoE4, indicating that full-length apoE3 and apoE4, but not apoE2, may be partially unfolded in vivo. The differences in stability and unfolding behavior are likely to contribute to the molecular basis for defects in lipid transport and neurological function induced by apoE polymorphism.
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Affiliation(s)
- Prathima Acharya
- Department of Chemistry and Biochemistry, University of the Sciences in Philadelphia, Philadelphia, PA 19104, USA
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Dzwolak W, Kato M, Taniguchi Y. Fourier transform infrared spectroscopy in high-pressure studies on proteins. BIOCHIMICA ET BIOPHYSICA ACTA 2002; 1595:131-44. [PMID: 11983392 DOI: 10.1016/s0167-4838(01)00340-5] [Citation(s) in RCA: 93] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 10/27/2022]
Abstract
Several aspects of the application of Fourier transform infrared spectroscopy (FTIR) in high-pressure studies on proteins are reviewed. Basic methodological considerations regarding spectral band assignments, quantitative analysis, and choice of pressure calibrants are also placed within the scope of this paper. This work attempts to evaluate recent developments in the field of high-pressure FTIR of proteins and its prospects for future. Particular attention is paid to the phenomenon of protein aggregation.
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Affiliation(s)
- Wojciech Dzwolak
- Department of Applied Chemistry, College of Science and Engineering, Ritsumeikan University, 1-1-1 Nojihigashi, Kusatsu, Shiga, Japan
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Chittchang M, Alur HH, Mitra AK, Johnston TP. Poly(L-lysine) as a model drug macromolecule with which to investigate secondary structure and membrane transport, part I: Physicochemical and stability studies. J Pharm Pharmacol 2002; 54:315-23. [PMID: 11902797 DOI: 10.1211/0022357021778556] [Citation(s) in RCA: 31] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/31/2022]
Abstract
Low oral bioavailability of therapeutic peptides and proteins generally results from their poor permeability through biological membranes and enzymatic degradation in the gastrointestinal tract. Since different secondary structures exhibit different physicochemical properties such as hydrophobicity, size and shape, changing the secondary structure of a therapeutic polypeptide may be another approach to increasing its membrane permeation. Poly(L-lysine) was used as a model polypeptide. The objectives of this study were to induce secondary structural changes in poly(L-lysine) and to determine the time course over which a given conformer was retained. In addition, the hydrophobicity of each secondary structure of poly(L-lysine) was assessed. The circular dichroism (CD) studies demonstrated that the conditions employed could successfully induce the desired secondary structural changes in poly(L-lysine). The alpha-helix conformer appeared to be more stable at 25 degrees C whereas the beta-sheet conformer could be preserved at 37 degrees C. On the other hand, the random coil conformer was retained at both temperatures. Significant losses of the alpha-helix and the beta-sheet conformers were observed when the pH was reduced. The change in ionic strength did not affect any of the conformers. The octanol/buffer partitioning studies indicated that the alpha-helix and the beta-sheet conformers exhibited significantly different (P < 0.05) hydrophobicities. In conclusion, variation of pH and temperature conditions can be used to induce secondary structural changes in poly(L-lysine). These changes are reversible when the stimuli are removed. The alpha-helix and the beta-sheet conformers of poly(L-lysine) are more lipophilic than the native random coil conformer. Thus, poly(L-lysine) may represent an ideal model polypeptide with which to further investigate the effects of secondary structure on membrane diffusion or permeation.
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Affiliation(s)
- Montakarn Chittchang
- Division of Pharmaceutical Sciences, School of Pharmacy, University of Missouri-Kansas City, MO 64110-2499, USA
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28
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Park C, Carlson MJ, Goddard WA. Solvent Effects on the Secondary Structures of Proteins. J Phys Chem A 1999. [DOI: 10.1021/jp9911189] [Citation(s) in RCA: 16] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/18/2022]
Affiliation(s)
- Changmoon Park
- Materials and Process Simulation Center, Beckman Institute (139-74), Division of Chemistry and Chemical Engineering, California Institute of Technology, Pasadena, California 91125
| | - Matt J. Carlson
- Materials and Process Simulation Center, Beckman Institute (139-74), Division of Chemistry and Chemical Engineering, California Institute of Technology, Pasadena, California 91125
| | - William A. Goddard
- Materials and Process Simulation Center, Beckman Institute (139-74), Division of Chemistry and Chemical Engineering, California Institute of Technology, Pasadena, California 91125
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Ichinose I, Mizuki S, Ohno S, Shiraishi H, Kunitake T. Preparation of Cross-Linked Ultrathin Films Based on Layer-by-Layer Assembly of Polymers. Polym J 1999. [DOI: 10.1295/polymj.31.1065] [Citation(s) in RCA: 22] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
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30
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Mitchell DC, Litman BJ. Effect of protein hydration on receptor conformation: decreased levels of bound water promote metarhodopsin II formation. Biochemistry 1999; 38:7617-23. [PMID: 10387000 DOI: 10.1021/bi990634m] [Citation(s) in RCA: 40] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
Neutral solutes were used to investigate the effects of osmotic stress both on the ability of rhodopsin to undergo its activating conformation change and on acyl chain packing in the rod outer segment (ROS) disk membrane. The equilibrium concentration of metarhodopsin II (MII), the conformation of photoactivated rhodopsin, which binds and activates transducin, was increased by glycerol, sucrose, and stachyose in a manner which was linear with osmolality. Analysis of this shift in equilibrium in terms of the dependence of ln(Keq) on osmolality revealed that 20 +/- 1 water molecules are released during the MI-to-MII transition at 20 degrees C, and at 35 degrees C 13 +/- 1 waters are released. At 35 degrees C the average time constant for MII formation was increased from 1.20 +/- 0.09 ms to 1.63 +/- 0.09 ms by addition of 1 osmolal sucrose or glycerol. The effect of the neutral solutes on acyl chain packing in the ROS disk membrane was assessed via measurements of the fluorescence lifetime and anisotropy decay of 1,6-diphenyl-1,3,5-hexatriene (DPH). Analysis of the anisotropy decay of DPH in terms of the rotational diffusion model showed that the angular width of the equilibrium orientational distribution of DPH about the membrane normal was progressively narrowed by increased osmolality. The parameter fv, which is proportional to the overlap between the DPH orientational probability distribution and a random orientational distribution, was reduced by the osmolytes in a manner which was linear with osmolality. This study highlights the potentially opposing interplay between the effect of membrane surface hydration on both the lipid bilayer and integral membrane protein structure. Our results further demonstrate that the binding and release of water molecules play an important role in modulating functional conformational changes for integral membrane proteins, as well as for soluble globular proteins.
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Affiliation(s)
- D C Mitchell
- Section of Fluorescence Studies, Laboratory of Membrane Biophysics and Biochemistry, National Institute on Alcohol Abuse and Alcoholism, Rockville, Maryland 20852, USA
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Enlund M, Mentell O, Flenninger A, Horneman G, Ronquist G. Evidence of cerebral dysfunction associated with isoflurane- or propofol based anaesthesia for orthognathic surgery, as assessed by biochemical and neuropsychological methods. Ups J Med Sci 1998; 103:43-59. [PMID: 9789971 DOI: 10.3109/03009739809178944] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
Abstract
A relationship has previously been described between individual mean isoflurane concentrations and the release of a marker of neuronal injury, adenylate kinase (AK), into the cerebrospinal fluid (CSF) after anaesthesia and orthognathic surgery. Likewise, reduced mental performance has been detected. Twenty-nine patients scheduled for orthognathic surgery were assigned to isoflurane- or propofol based anaesthesia, which was adjusted to a defined level with the aid of processed EEG and quantitative surface EMG. In the case of a mean arterial pressure (MAP) < 50 mmHg a phenylephrine infusion was started to keep the MAP above the minimal level, otherwise no regard was paid to the blood pressure, which never exceeded normal values. A lumbar puncture for CSF sampling was performed approximately 20 h postoperatively. The CSF sample was analysed for AK activity. Neuropsychological tests were performed the day prior to surgery and again in the period 4-8 weeks postoperatively. Five patients were re-examined by psychometry 12-30 months later. A release of AK into CSF was confirmed, equal in both groups. Correlation with the anaesthetic dose given was poor. Five patients from each group failed significantly in the postoperative neuropsychological tests. They differed in several demographic respects from the others. When five of the failed patients were re-examined 12-30 months later, three patients still performed poorly in the tests. Biochemical and neuropsychological disturbances were recorded in several patients objected to orthognathic surgery. The underlying mechanisms are unclear, including the role of the anaesthetic drugs or surgery itself.
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Affiliation(s)
- M Enlund
- Department of Anaesthesia and Intensive Care, Central Hospital, Västerås, Sweden
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Lee SM, Lin SY. Differentiation of the maturity of cataractous human lens capsules according to changes in protein secondary structures determined by Fourier-transformed infrared spectroscopy. AUSTRALIAN AND NEW ZEALAND JOURNAL OF OPHTHALMOLOGY 1997; 25:233-8. [PMID: 9296300 DOI: 10.1111/j.1442-9071.1997.tb01399.x] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/05/2023]
Abstract
PURPOSE Cataract-induced alterations in the protein secondary structure of human lens capsules in different maturity of cataractous patients was investigated. METHODS Fourier-transformed infrared (FT-IR) spectroscopy with Fourier self-deconvolution and curve-fitting algorithms was used. Twenty-seven immature and four mature cataractous patients (previously classified through observations of the depth of the shadow cast by the iris on oblique illumination) were investigated in the present study. RESULTS Two groups with progressive cataract formation could be effectively redifferentiated and re-arranged. In the first group, all the peak positions were the same and the peak at 1651 cm-1 assigned to the alpha-helix structure was predominant, but the structural compositions of the beta-sheet and beta-turn changed with progressive cataractogenesis. In the second group, in which cataract formation was more advanced, the peak at 1651 cm-1 assigned to the alpha-helix structure shifted to 1658 cm-1 and a new peak appeared at 1647 cm-1, due to random coil structure; the structural compositions of triple helix significantly decreased but the compositions of the beta-sheet and beta-turn slightly increased. Amides II and III of the IR spectra seemed to be less changed in secondary structures. CONCLUSIONS These results suggest that FT-IR spectroscopy with Fourier self-deconvolution and curve-fitting programs can be used as a diagnostic tool for the determination of the cataractous maturity of human lens capsules.
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Affiliation(s)
- S M Lee
- Department of Ophthalmology, Veterans General Hospital, Taipei, Taiwan, ROC
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Roque RL, Herrera S, Yeh TJ, Philip J, Borisavljevic TL, Brunick L, Miles A, Haritunians T, Addy C, Bada RA, Vaghefi H, Matsumoto SS, Piccionelli GA, Rodriguez L, Oppenheimer SB. Cell adhesion mechanisms: modeling using derivatized beads and sea urchin cell systems. Acta Histochem 1996; 98:441-51. [PMID: 8960308 DOI: 10.1016/s0065-1281(96)80011-0] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/03/2023]
Abstract
Agarose beads derivatized with amino acids, peptides, carbohydrates and lectins were used to systematically determine what types of molecules, isolated from all others, can make adhesive bonds strong enough to hold cell-like beads together. The results indicated that strong adhesion occurred when at least one of the two members of certain bead pairs was derivatized with molecules that were dimers or trimers but not monomers. Also, beads derivatized with phosphorylated amino acids, but not their non-phosphorylated counterparts, adhered to beads derivatized with positively charged peptides. Adhesion was sensitive to ionic strength and pH of the medium. It was proposed that adhesion occurred between the phosphate groups of the phosphoamino acids and amino and guanidinium groups of the peptides. Cooperative bonding can explain the stability of the adhesion observed in this system. Information gained from the bead modeling work was used to design experiments to examine the role of phosphorylated molecules in modulating adhesion in sea urchin systems. Phosphoamino acids inhibited sperm-egg interaction, but not reaggregation of blastula cells. Inhibitors of alkaline phosphatase, however, did inhibit reaggregation. The results suggest that cell surface phosphorylated molecules may modulate cellular adhesiveness, in some systems promoting, while in others inhibiting adhesion.
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Affiliation(s)
- R L Roque
- Center for Cancer and Developmental Biology, California State University, Northridge 91330-8303, USA
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Johansson JS, Eckenhoff RG. Minimum structural requirement for an inhalational anesthetic binding site on a protein target. BIOCHIMICA ET BIOPHYSICA ACTA 1996; 1290:63-8. [PMID: 8645708 DOI: 10.1016/0304-4165(95)00187-5] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/01/2023]
Abstract
The present study makes use of direct photoaffinity labeling and fluorescence and circular dichroism spectroscopy to examine the interaction of the inhalational anesthetic halothane with the uncharged alpha-helical form of poly(L-lysine) over a range of chain lengths. Halothane bound specifically to long chain homopolymers (190 to 1060 residues), reaching a stable stoichiometry of 1 halothane to 160 lysine residues in polymers longer than 300 residues. Halothane bound only non-specifically to an alpha-helical 30 residue polymer and to all of the polymers in their charged, random coil form. The data suggest that halothane binding is a function of supersecondary structure whereby intramolecular helix-helix clusters form in the longer polymers, resulting in the creation of confined hydrophobic domains. Circular dichroism spectroscopy cannot demonstrate changes in poly(L-lysine) secondary structure at any chain length with up to 12 mM halothane, suggesting that extensive hydrogen bond disruption by the anesthetic does not occur.
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Affiliation(s)
- J S Johansson
- Department of Anesthesiology, University of Pennsylvania Medical Center, Philadelphia, 19104-4283, USA
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36
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Robinson CR, Sligar SG. Hydrostatic and osmotic pressure as tools to study macromolecular recognition. Methods Enzymol 1995; 259:395-427. [PMID: 8538464 DOI: 10.1016/0076-6879(95)59054-4] [Citation(s) in RCA: 87] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/31/2023]
Abstract
Clearly, hydrostatic and osmotic pressure techniques offer unique potential in the study of fundamental problems of molecular recognition in biological systems. With the recent advances in technology such investigations are rapidly becoming commonplace. We look forward to further advances and their report in succeeding compendiums such as this volume.
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Affiliation(s)
- C R Robinson
- Department of Biology, Massachusetts Institute of Technology, Cambridge 02139, USA
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37
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Chiou JS, Ueda I. Ethanol unfolds firefly luciferase while competitive inhibitors antagonize unfolding: DSC and FTIR analyses. J Pharm Biomed Anal 1994; 12:969-75. [PMID: 7819382 DOI: 10.1016/0731-7085(94)00045-x] [Citation(s) in RCA: 16] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/27/2023]
Abstract
Firefly luciferase has gained popularity as a protein model in elucidating anaesthesia mechanism because the bioluminescence of the purified enzyme system is extremely sensitive to volatile anaesthetics. This study analysed the thermal unfolding of firefly luciferase by differential scanning calorimetry (DSC) and Fourier transform infrared spectroscopy (FTIR). DSC showed that the transition of firefly luciferase from the folded (N) to unfolded (D) state occurred at 41.7 degrees C with the excess heat flow of 1.6 cal g-1 protein. Ethanol decreased the transition temperature dose dependently. In contrast, luciferin competitors, anilinonaphthalenesulphonate (ANS), toluidinonaphthalenesulphonate (TNS), and myristic acid increased the transition temperature. The competitive inhibitors antagonized unfolding and stabilized the N-state. Ethanol promoted unfolding and stabilized the D-state. Temperature scan by FTIR agreed with the DSC data. The intensities of amide-I' and amide-II' bands started to increase at 20-25 degrees C. This temperature coincides with the temperature where the bioluminescence of firefly luciferase is maximal. The unfolding effect of ethanol was evident even at 5 degrees C. ANS, TNS, and myristic acid completely protected the enzyme from the thermal unfolding. This is the first demonstration that the noncompetitive inhibitors induce the isothermal first-order phase transition in a functional protein, whereas competitive inhibitors protect the enzyme from thermal unfolding. The action mode of competitive inhibitors on firefly luciferase is completely different from that of noncompetitive inhibitors.
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Affiliation(s)
- J S Chiou
- Department of Anesthesia, DVA Medical Center, Salt Lake City, UT 84148
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Shibata A, Yamamoto M, Yamashita T, Chiou JS, Kamaya H, Ueda I. Biphasic effects of alcohols on the phase transition of poly(L-lysine) between alpha-helix and beta-sheet conformations. Biochemistry 1992; 31:5728-33. [PMID: 1610821 DOI: 10.1021/bi00140a006] [Citation(s) in RCA: 39] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/27/2022]
Abstract
Poly(L-lysine) exists as a random-coil at neutral pH, an alpha-helix at alkaline pH, and a beta-sheet when the alpha-helix poly(L-lysine) is heated. The present Fourier-transform infrared (FTIR) study showed that short-chain alcohols (methanol, ethanol, and 2-propanol) partially transformed alpha-helix poly(L-lysine) to beta-sheet when their concentrations were low. At higher concentrations, however, these alcohols reversed the reaction, and the alcohol-induced beta-sheet was transformed back to alpha-helix structure. The reversal occurred at 1.40 M methanol, 0.96 M ethanol, and 0.55 M 2-propanol. The alcohol effects on the secondary structure were further investigated by circular dichroism (CD) on the thermally induced beta-sheet poly(L-lysine). Methanol, ethanol, and 1-propanol, but not 1-butanol, shifted the negative mean-residue ellipticity at 217 nm of the beta-sheet poly(L-lysine) to the positive side at low concentrations of the alcohols and to the negative side at high concentrations. With 1-butanol, only the positive-side shift was observed. The positive-side shift at low concentrations of alcohols indicates enhancement of the hydrophobic interactions among the side chains of the polypeptide in the beta-sheet conformation. The negative-side shift indicates a partial transformation to alpha-helix. The shift from the positive to negative side occurred at 7.1 M methanol, 4.6 M ethanol, and 3.1 M 1-propanol. The alcohol concentrations for the beta-to-alpha transition were higher in the CD study than in the IR study.(ABSTRACT TRUNCATED AT 250 WORDS)
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Affiliation(s)
- A Shibata
- Faculty of Pharmaceutical Sciences, Tokushima University, Japan
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