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Ugur K, Erman F, Turkoglu S, Aydin Y, Aksoy A, Lale A, Karagöz ZK, Ugur I, Akkoc RF, Yalniz M. Asprosin, visfatin and subfatin as new biomarkers of obesity and metabolic syndrome. Eur Rev Med Pharmacol Sci 2022; 26:2124-2133. [PMID: 35363362 DOI: 10.26355/eurrev_202203_28360] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Subscribe] [Scholar Register] [Indexed: 06/14/2023]
Abstract
OBJECTIVE Metabolic syndrome (MetS) and obesity are important public health problems associated with adipose tissue mass. Asprosin, visfatin, and subfatin are new members of which fate in MetS and obesity has not been fully revealed yet. Thus, this study was to investigate the association between asprosin, visfatin, subfatin, and biochemical values, demographic data, and body composition measurement values in MetS patients with and without obesity. PATIENTS AND METHODS Blood samples were taken from a total of 90 people, including 31 MetS patients with obesity, 29 MetS patients without obesity, and 30 healthy (control). Asprosin, visfatin, and subfatin were studied by the ELISA method. RESULTS There was a negative correlation between asprosin and Body Mass Index (BMI) in the MetS + Obese group. The correlations between asprosin and urea and fasting insulin (FI) levels in the MetS group were positive and statistically significant (p < 0.05). While there was a statistically significant negative correlation (p < 0.05) between visfatin and BMI in the MetS + Obese group, the correlation with waist circumference in the MetS + Obese and MetS groups was statistically significant and negative (p < 0.05). There was a statistically significant negative relationship (p < 0.05) between aspartate aminotransferase value and visfatin. The results between visfatin values and asprosin and subfatin in all groups were significant (p < 0.05). CONCLUSIONS There is a direct relationship between circulating amounts of asprosin, visfatin, and subfatin hormones and age, weight, height, diastolic blood pressure, high-density lipoprotein-cholesterol, aspartate aminotransferase, alanine transaminase, and creatinine. Therefore, asprosin, visfatin, and subfatin hormones are the new biomarkers of metabolic turbulence.
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Affiliation(s)
- K Ugur
- Department of Internal Medicine (Endocrinology and Metabolism Diseases), Faculty of Medicine, Fırat University, Elazig, Turkey.
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2
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Le P, Kunold E, Macsics R, Rox K, Jennings MC, Ugur I, Reinecke M, Chaves-Moreno D, Hackl MW, Fetzer C, Mandl FAM, Lehmann J, Korotkov VS, Hacker SM, Kuster B, Antes I, Pieper DH, Rohde M, Wuest WM, Medina E, Sieber SA. Repurposing human kinase inhibitors to create an antibiotic active against drug-resistant Staphylococcus aureus, persisters and biofilms. Nat Chem 2020; 12:145-158. [PMID: 31844194 PMCID: PMC6994260 DOI: 10.1038/s41557-019-0378-7] [Citation(s) in RCA: 68] [Impact Index Per Article: 17.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/10/2019] [Accepted: 10/15/2019] [Indexed: 12/31/2022]
Abstract
New drugs are desperately needed to combat methicillin-resistant Staphylococcus aureus (MRSA) infections. Here, we report screening commercial kinase inhibitors for antibacterial activity and found the anticancer drug sorafenib as major hit that effectively kills MRSA strains. Varying the key structural features led to the identification of a potent analogue, PK150, that showed antibacterial activity against several pathogenic strains at submicromolar concentrations. Furthermore, this antibiotic eliminated challenging persisters as well as established biofilms. PK150 holds promising therapeutic potential as it did not induce in vitro resistance, and shows oral bioavailability and in vivo efficacy. Analysis of the mode of action using chemical proteomics revealed several targets, which included interference with menaquinone biosynthesis by inhibiting demethylmenaquinone methyltransferase and the stimulation of protein secretion by altering the activity of signal peptidase IB. Reduced endogenous menaquinone levels along with enhanced levels of extracellular proteins of PK150-treated bacteria support this target hypothesis. The associated antibiotic effects, especially the lack of resistance development, probably stem from the compound's polypharmacology.
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Affiliation(s)
- Philipp Le
- Center for Integrated Protein Science at the Department of Chemistry, Technische Universität München, Garching bei München, Germany
- Chair of Organic Chemistry II, Technische Universität München, Garching bei München, Germany
| | - Elena Kunold
- Center for Integrated Protein Science at the Department of Chemistry, Technische Universität München, Garching bei München, Germany
- Chair of Organic Chemistry II, Technische Universität München, Garching bei München, Germany
- SciLifeLab, Department of Oncology-Pathology, Karolinska Institutet, Solna, Sweden
| | - Robert Macsics
- Center for Integrated Protein Science at the Department of Chemistry, Technische Universität München, Garching bei München, Germany
- Chair of Organic Chemistry II, Technische Universität München, Garching bei München, Germany
| | - Katharina Rox
- Department of Chemical Biology, Helmholtz Centre for Infection Research, Braunschweig, Germany
- German Centre for Infection Research, Partner Site Braunschweig-Hannover, Hannover, Germany
| | - Megan C Jennings
- Department of Chemistry, Temple University, Philadelphia, PA, USA
| | - Ilke Ugur
- Center for Integrated Protein Science, TUM School of Life Sciences, Technische Universität München, Freising, Germany
| | - Maria Reinecke
- Chair of Proteomics and Bioanalytics, Technische Universität München, Freising, Germany
- German Cancer Consortium, Partner Site Munich, Munich, Germany
- German Cancer Research Center, Heidelberg, Germany
| | - Diego Chaves-Moreno
- Microbial Interactions and Processes Research Group, Helmholtz Centre for Infection Research, Braunschweig, Germany
| | - Mathias W Hackl
- Center for Integrated Protein Science at the Department of Chemistry, Technische Universität München, Garching bei München, Germany
- Chair of Organic Chemistry II, Technische Universität München, Garching bei München, Germany
| | - Christian Fetzer
- Center for Integrated Protein Science at the Department of Chemistry, Technische Universität München, Garching bei München, Germany
- Chair of Organic Chemistry II, Technische Universität München, Garching bei München, Germany
| | - Franziska A M Mandl
- Center for Integrated Protein Science at the Department of Chemistry, Technische Universität München, Garching bei München, Germany
- Chair of Organic Chemistry II, Technische Universität München, Garching bei München, Germany
| | - Johannes Lehmann
- Center for Integrated Protein Science at the Department of Chemistry, Technische Universität München, Garching bei München, Germany
- Chair of Organic Chemistry II, Technische Universität München, Garching bei München, Germany
| | - Vadim S Korotkov
- Center for Integrated Protein Science at the Department of Chemistry, Technische Universität München, Garching bei München, Germany
- Chair of Organic Chemistry II, Technische Universität München, Garching bei München, Germany
| | - Stephan M Hacker
- Department of Chemistry, Technische Universität München, Garching bei München, Germany
| | - Bernhard Kuster
- Chair of Proteomics and Bioanalytics, Technische Universität München, Freising, Germany
- German Cancer Consortium, Partner Site Munich, Munich, Germany
- German Cancer Research Center, Heidelberg, Germany
- Center for Integrated Protein Science Munich, Garching bei München, Germany
| | - Iris Antes
- Center for Integrated Protein Science, TUM School of Life Sciences, Technische Universität München, Freising, Germany
| | - Dietmar H Pieper
- Microbial Interactions and Processes Research Group, Helmholtz Centre for Infection Research, Braunschweig, Germany
| | - Manfred Rohde
- Central Facility for Microscopy, Helmholtz Centre for Infection Research, Braunschweig, Germany
| | - William M Wuest
- Department of Chemistry, Emory University, Atlanta, GA, USA
- Emory Antibiotic Resistance Center, Emory School of Medicine, Atlanta, GA, USA
| | - Eva Medina
- Infection Immunology Research Group, Helmholtz Centre for Infection Research, Braunschweig, Germany
| | - Stephan A Sieber
- Center for Integrated Protein Science at the Department of Chemistry, Technische Universität München, Garching bei München, Germany.
- Chair of Organic Chemistry II, Technische Universität München, Garching bei München, Germany.
- Helmholtz Institute for Pharmaceutical Research Saarland, Helmholtz Centre for Infection Research, Saarbrücken, Germany.
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Ugur I, Chandrasekhar P. Proton relay network in P450cam formed upon docking of putidaredoxin. Proteins 2019; 88:558-572. [PMID: 31597203 DOI: 10.1002/prot.25835] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/22/2019] [Revised: 09/13/2019] [Accepted: 09/28/2019] [Indexed: 11/08/2022]
Abstract
Cytochromes P450 are versatile heme-based enzymes responsible for vital life processes. Of these, P450cam (substrate camphor) has been most studied. Despite this, precise mechanisms of the key O─O cleavage step remain partly elusive to date; effects observed in various enzyme mutants remain partly unexplained. We have carried out extended (to 1000 ns) MM-MD and follow-on quantum mechanics/molecular mechanics computations, both on the well-studied FeOO state and on Cpd(0) (compound 0). Our simulations include (all camphor-bound): (a) WT (wild type), FeOO state. (b) WT, Cpd(0). (c) Pdx (Putidaredoxin, redox partner of P450)-docked-WT, FeOO state. (d) Pdx-docked WT, Cpd(0). (e) Pdx-docked T252A mutant, Cpd(0). Among our key findings: (a) Effect of Pdx docking appears to go far beyond that indicated in prior studies: it leads to specific alterations in secondary structure that create the crucial proton relay network. (b) Specific proton relay networks we identify are: FeOO(H)⋯T252⋯nH 2 O⋯D251 in WT; FeOO(H)⋯nH 2 O⋯D251 in T252A mutant; both occur with Pdx docking. (c) Direct interaction of D251 with -FeOOH is, respectively, rare/frequent in WT/T252A mutant. (d) In WT, T252 is in the proton relay network. (e) Positioning of camphor appears significant: when camphor is part of H-bonding network, second protonation appears to be facilitated.
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Affiliation(s)
- Ilke Ugur
- Research Division, Ashwin-Ushas Corporation, Marlboro, New Jersey
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Ugur I, Schroft M, Marion A, Glaser M, Antes I. Predicting the bioactive conformations of macrocycles: a molecular dynamics-based docking procedure with DynaDock. J Mol Model 2019; 25:197. [PMID: 31222506 DOI: 10.1007/s00894-019-4077-5] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/13/2018] [Accepted: 05/28/2019] [Indexed: 02/06/2023]
Abstract
Macrocyclic compounds are of growing interest as a new class of therapeutics, especially as inhibitors binding to protein-protein interfaces. As molecular modeling is a well-established complimentary tool in modern drug design, the number of attempts to develop reliable docking strategies and algorithms to accurately predict the binding mode of macrocycles is rising continuously. Standard molecular docking approaches need to be adapted to this application, as a comprehensive yet efficient sampling of all ring conformations of the macrocycle is necessary. To overcome this issue, we designed a molecular dynamics-based docking protocol for macrocycles, in which the challenging sampling step is addressed by conventional molecular dynamics (750 ns) simulations performed at moderately high temperature (370 K). Consecutive flexible docking with the DynaDock approach based on multiple, pre-sampled ring conformations yields highly accurate poses with ligand RMSD values lower than 1.8 Å. We further investigated the value of molecular dynamics-based complex stability estimations for pose selection and discuss its applicability in combination with standard binding free energy estimations for assessing the quality of poses in future blind docking studies.
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Affiliation(s)
- Ilke Ugur
- Center for Integrated Protein Science at the Department for Biosciences, Technische Universität München, Emil-Erlenmeyer-Forum 8, 85354, Freising, Germany
- Department of Chemistry, Middle East Technical University, 06800, Ankara, Turkey
| | - Maja Schroft
- Center for Integrated Protein Science at the Department for Biosciences, Technische Universität München, Emil-Erlenmeyer-Forum 8, 85354, Freising, Germany
| | - Antoine Marion
- Center for Integrated Protein Science at the Department for Biosciences, Technische Universität München, Emil-Erlenmeyer-Forum 8, 85354, Freising, Germany
- Department of Chemistry, Middle East Technical University, 06800, Ankara, Turkey
| | - Manuel Glaser
- Center for Integrated Protein Science at the Department for Biosciences, Technische Universität München, Emil-Erlenmeyer-Forum 8, 85354, Freising, Germany
| | - Iris Antes
- Center for Integrated Protein Science at the Department for Biosciences, Technische Universität München, Emil-Erlenmeyer-Forum 8, 85354, Freising, Germany.
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Bali SK, Marion A, Ugur I, Dikmenli AK, Catak S, Aviyente V. Activity of Topotecan toward the DNA/Topoisomerase I Complex: A Theoretical Rationalization. Biochemistry 2018; 57:1542-1551. [DOI: 10.1021/acs.biochem.7b01297] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023]
Affiliation(s)
- Semiha Kevser Bali
- Department of Chemistry, Faculty of Arts and Sciences, Boğaziçi University, Bebek, 34342 Istanbul, Turkey
| | - Antoine Marion
- Department of Chemistry, Middle East Technical University, 06800 Ankara, Turkey
| | - Ilke Ugur
- Department of Lifesciences, Technical University of Munich, 80333 Munich, Germany
| | - Ayse Kumru Dikmenli
- Department of Chemistry and Chemical Biology, MacMaster University, Hamilton, Ontario L8S4L8, Canada
| | - Saron Catak
- Department of Chemistry, Faculty of Arts and Sciences, Boğaziçi University, Bebek, 34342 Istanbul, Turkey
| | - Viktorya Aviyente
- Department of Chemistry, Faculty of Arts and Sciences, Boğaziçi University, Bebek, 34342 Istanbul, Turkey
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Ugur I, Cinar SA, Dedeoglu B, Aviyente V, Hawthorne MF, Liu P, Liu F, Houk KN, Jiménez-Osés G. 1,3-Dipolar Cycloaddition Reactions of Low-Valent Rhodium and Iridium Complexes with Arylnitrile N-Oxides. J Org Chem 2017; 82:5096-5101. [PMID: 28414468 PMCID: PMC5679111 DOI: 10.1021/acs.joc.7b00282] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
The reactions between low-valent Rh(I) and Ir(I) metal-carbonyl complexes and arylnitrile oxides possess the electronic and structural features of 1,3-dipolar cycloadditions. Density functional theory (DFT) calculations on these reactions, involving both cyclopentadienyl and carboranyl ligands on the metal carbonyl, explain the ease of the chemical processes and the stabilities of the resulting metallaisoxazolin-5-ones. The metal-carbonyl bond has partial double bond character according to the Wiberg index calculated through NBO analysis, and so the reaction can be considered a normal 1,3-dipolar cycloaddition involving M═C bonds. The rates of formation of the metallacycloadducts are controlled by distortion energy, analogous to their organic counterparts. The superior ability of anionic Ir complexes to share their electron density and accommodate higher oxidation states explains their calculated higher reactivity toward cycloaddition, as compared to Rh analogues.
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Affiliation(s)
- Ilke Ugur
- Department of Chemistry, Bogazici University, Bebek, Istanbul 34342, Turkey
- Department of Chemistry and Biochemistry, University of California, Los Angeles, Los Angeles, California 90095-1569, United States
| | | | - Burcu Dedeoglu
- Foundations Development Directorate, Sabancı University, Tuzla-Orhanlı, Istanbul 34956, Turkey
| | - Viktorya Aviyente
- Department of Chemistry, Bogazici University, Bebek, Istanbul 34342, Turkey
| | - M. Frederick Hawthorne
- International Institute of Nano and Molecular Medicine, University of Missouri, Columbia, Missouri 65211-3450, United States
| | - Peng Liu
- Department of Chemistry and Biochemistry, University of California, Los Angeles, Los Angeles, California 90095-1569, United States
| | - Fang Liu
- Department of Chemistry and Biochemistry, University of California, Los Angeles, Los Angeles, California 90095-1569, United States
| | - K. N. Houk
- Department of Chemistry and Biochemistry, University of California, Los Angeles, Los Angeles, California 90095-1569, United States
| | - Gonzalo Jiménez-Osés
- Departamento de Química, Centro de Investigación en Síntesis Química, Universidad de La Rioja, 26006 Logroño, La Rioja, Spain
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Mandl FA, Kirsch VC, Ugur I, Kunold E, Vomacka J, Fetzer C, Schneider S, Richter K, Fuchs TM, Antes I, Sieber SA. Naturstoffbasierte Aminoepoxybenzochinone inhibieren das Wachstum verschiedener Serovare des Gram-negativen KrankheitserregersSalmonelladurch Abschwächen der bakteriellen Stressabwehr. Angew Chem Int Ed Engl 2016. [DOI: 10.1002/ange.201607338] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
Affiliation(s)
- Franziska A. Mandl
- Center for Integrated Protein Science, Department Chemie; Technische Universität München; Lichtenbergstraße 4 85747 Garching Deutschland
| | - Volker C. Kirsch
- Center for Integrated Protein Science, Department Chemie; Technische Universität München; Lichtenbergstraße 4 85747 Garching Deutschland
| | - Ilke Ugur
- Center for Integrated Protein Science; Department für Biowissenschaften; Technische Universität München; Erlenmeyer-Forum 8 85354 Freising Deutschland
| | - Elena Kunold
- Center for Integrated Protein Science, Department Chemie; Technische Universität München; Lichtenbergstraße 4 85747 Garching Deutschland
| | - Jan Vomacka
- Center for Integrated Protein Science, Department Chemie; Technische Universität München; Lichtenbergstraße 4 85747 Garching Deutschland
| | - Christian Fetzer
- Center for Integrated Protein Science, Department Chemie; Technische Universität München; Lichtenbergstraße 4 85747 Garching Deutschland
| | - Sabine Schneider
- Center for Integrated Protein Science, Department Chemie; Technische Universität München; Lichtenbergstraße 4 85747 Garching Deutschland
| | - Klaus Richter
- Center for Integrated Protein Science, Department Chemie; Technische Universität München; Lichtenbergstraße 4 85747 Garching Deutschland
| | - Thilo M. Fuchs
- Lehrstuhl für Mikrobielle Ökologie; Zentralinstitut für Ernährungs- und Lebensmittelforschung; Technische Universität München; Weihenstephaner Berg 3 85354 Freising Deutschland
| | - Iris Antes
- Center for Integrated Protein Science; Department für Biowissenschaften; Technische Universität München; Erlenmeyer-Forum 8 85354 Freising Deutschland
| | - Stephan A. Sieber
- Center for Integrated Protein Science, Department Chemie; Technische Universität München; Lichtenbergstraße 4 85747 Garching Deutschland
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Ince HH, Konuklar FAS, Ugur I, Ozcan ÖA, Sayadi M, Feig M, Aviyente V. Role of then+1 amino acid residue on the deamidation of asparagine in pentapeptides. Mol Phys 2015. [DOI: 10.1080/00268976.2015.1068394] [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: 10/23/2022]
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Ugur I, Marion A, Aviyente V, Monard G. Why Does Asn71 Deamidate Faster Than Asn15 in the Enzyme Triosephosphate Isomerase? Answers from Microsecond Molecular Dynamics Simulation and QM/MM Free Energy Calculations. Biochemistry 2015; 54:1429-39. [DOI: 10.1021/bi5008047] [Citation(s) in RCA: 11] [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: 11/29/2022]
Affiliation(s)
- Ilke Ugur
- Université de Lorraine, UMR 7565 SRSMC, Boulevard des Aiguillettes B.P.
70239, F-54506 Vandoeuvre-les-Nancy, France
- CNRS, UMR 7565
SRSMC, Boulevard des Aiguillettes
B.P. 70239, F-54506 Vandoeuvre-les-Nancy, France
- Department
of Chemistry, Boğaziçi University, 34342 Bebek, Istanbul, Turkey
| | - Antoine Marion
- Université de Lorraine, UMR 7565 SRSMC, Boulevard des Aiguillettes B.P.
70239, F-54506 Vandoeuvre-les-Nancy, France
- CNRS, UMR 7565
SRSMC, Boulevard des Aiguillettes
B.P. 70239, F-54506 Vandoeuvre-les-Nancy, France
| | - Viktorya Aviyente
- Department
of Chemistry, Boğaziçi University, 34342 Bebek, Istanbul, Turkey
| | - Gerald Monard
- Université de Lorraine, UMR 7565 SRSMC, Boulevard des Aiguillettes B.P.
70239, F-54506 Vandoeuvre-les-Nancy, France
- CNRS, UMR 7565
SRSMC, Boulevard des Aiguillettes
B.P. 70239, F-54506 Vandoeuvre-les-Nancy, France
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Ugur I, Marion A, Parant S, Jensen JH, Monard G. Rationalization of the pKa Values of Alcohols and Thiols Using Atomic Charge Descriptors and Its Application to the Prediction of Amino Acid pKa’s. J Chem Inf Model 2014; 54:2200-13. [DOI: 10.1021/ci500079w] [Citation(s) in RCA: 52] [Impact Index Per Article: 5.2] [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)
- Ilke Ugur
- Université de Lorraine, UMR 7565 SRSMC, Boulevard des Aiguillettes B.P. 70239, F-54506 Vandoeuvre-les-Nancy, France
- CNRS, UMR 7565 SRSMC, Boulevard
des Aiguillettes B.P. 70239, F-54506 Vandoeuvre-les-Nancy, France
- Department
of Chemistry, Boğaziçi University, 34342 Bebek, Istanbul, Turkey
| | - Antoine Marion
- Université de Lorraine, UMR 7565 SRSMC, Boulevard des Aiguillettes B.P. 70239, F-54506 Vandoeuvre-les-Nancy, France
- CNRS, UMR 7565 SRSMC, Boulevard
des Aiguillettes B.P. 70239, F-54506 Vandoeuvre-les-Nancy, France
| | - Stéphane Parant
- Université de Lorraine, UMR 7565 SRSMC, Boulevard des Aiguillettes B.P. 70239, F-54506 Vandoeuvre-les-Nancy, France
- CNRS, UMR 7565 SRSMC, Boulevard
des Aiguillettes B.P. 70239, F-54506 Vandoeuvre-les-Nancy, France
| | - Jan H. Jensen
- Department
of Chemistry, University of Copenhagen, Copenhagen, Denmark
| | - Gerald Monard
- Université de Lorraine, UMR 7565 SRSMC, Boulevard des Aiguillettes B.P. 70239, F-54506 Vandoeuvre-les-Nancy, France
- CNRS, UMR 7565 SRSMC, Boulevard
des Aiguillettes B.P. 70239, F-54506 Vandoeuvre-les-Nancy, France
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Ugur I, Sengun N, Demirdag S, Altindag R. Analysis of the alterations in porosity features of some natural stones due to thermal effect. Ultrasonics 2014; 54:1332-1336. [PMID: 24529822 DOI: 10.1016/j.ultras.2014.01.013] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/17/2013] [Revised: 01/23/2014] [Accepted: 01/23/2014] [Indexed: 06/03/2023]
Abstract
Three types of commercially available carbonate rocks were used in the study to determine the effect of thermal treatment in the range from 100 °C to 500 °C on porosity features in terms of two different approaches such as pore shape factor and quality index values. The ratio of the ultrasonic velocity measurements before and after water saturation was used to differentiate porosity of pores from porosity of cracks under varying temperatures. It was found that, pores in Burdur Beige and Usak White are in the form of cracks, which are situated through inner structure. On the other hand, pores in Patara Limestone are in the form of porosity with lower pore shape factor values. Quality index calculation is another approach based on the comparison of the measured and theoretical ultrasonic velocity values. When the rocks were subjected to higher temperatures, internal stress was developed, crack lengths and numbers were increased and finally the higher pore shape factor and lower quality index values were obtained. This situation was proven by the higher water absorption values for all the stone types with the higher pore shape factor and lower quality index values depend on the noticeable increase in effective porosity values.
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Affiliation(s)
- I Ugur
- Mining Engineering Department, Suleyman Demirel University, 32260 Isparta, Turkey.
| | - N Sengun
- Mining Engineering Department, Suleyman Demirel University, 32260 Isparta, Turkey
| | - S Demirdag
- Mining Engineering Department, Suleyman Demirel University, 32260 Isparta, Turkey
| | - R Altindag
- Mining Engineering Department, Suleyman Demirel University, 32260 Isparta, Turkey
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Ugur I, Aviyente V, Monard G. Initiation of the reaction of deamidation in triosephosphate isomerase: investigations by means of molecular dynamics simulations. J Phys Chem B 2012; 116:6288-301. [PMID: 22574817 DOI: 10.1021/jp3013305] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
Deamidation of asparagine is the spontaneous degradation of this residue into aspartic acid. The kinetics of this slow reaction is mainly dependent on the nature of the adjacent amino acid that follows asparagine in a peptide or protein primary sequence. In the homodimer triosephosphate isomerase (TPI), there are two main deamidation sites per subunit: Asn15-Gly16 and Asn71-Gly72 for which deamidation dynamics are known to be interrelated. In this study, we investigate the initiation of the deamidation reaction in TPI by means of molecular dynamics. Simulations based on classical AMBER force field are performed in a 60 to 90 ns time scale for six distinct samples. Conformational changes, desolvation effects, and hydrogen bond networks are analyzed to interpret the experimental findings and previous quantum mechanical (QM) results. Results that are based on desolvation analysis clarify the assignments in the literature about the different behaviors of two deamidating sites in TPI. Conformational analysis supports findings suggested by QM studies: the most favorable reaction mechanism is the one that yields to succinimide intermediate via one or two step routes. The mechanism leading to the succinimide intermediate most likely involves the formation of a tetrahedral intermediate that is formed either directly from asparagine or via a side chain tautomer intermediate. In all cases, surrounding water molecules are present to assist the reaction.
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Affiliation(s)
- Ilke Ugur
- Department of Chemistry, Boğaziçi University, 34342 Bebek, Istanbul, Turkey
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Kara P, Ugur I, Misirlioglu C, Demirkasimoglu T, Sanri E, Elgin Y, Ozgen A, Yurukoglu T, Ozdamar N, Guney Y. 9113 Palliative radiation oncologic therapy in lung cancer with superior vena cava syndrome. EJC Suppl 2009. [DOI: 10.1016/s1359-6349(09)71826-9] [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: 11/16/2022] Open
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