title: Species-Specific Thiol-Disulfide Equilibrium Constant: A Tool To Characterize Redox Transitions of Biological Importance.
abstract: Microscopic redox equilibrium constants, a new species-specific type of physicochemical parameters, were introduced and determined to quantify thiol-disulfide equilibria of biological significance. The thiol-disulfide redox equilibria of glutathione with cysteamine, cysteine, and homocysteine were approached from both sides, and the equilibrium mixtures were analyzed by quantitative NMR methods to characterize the highly composite, co-dependent acid-base and redox equilibria. The directly obtained, pH-dependent, conditional constants were then decomposed by a new evaluation method, resulting in pH-independent, microscopic redox equilibrium constants for the first time. The 80 different, microscopic redox equilibrium constant values show close correlation with the respective thiolate basicities and provide sound means for the development of potent agents against oxidative stress.
authors.affiliation: Department of Pharmaceutical Chemistry, Semmelweis University, Budapest, 1085 Hungary.|Research Group of Drugs of Abuse and Doping Agents, Hungarian Academy of Sciences Budapest, 1051 Hungary.
authors.forename: Arash
authors.initials: A
authors.lastname: Mirzahosseini
authors.affiliation: Department of Pharmaceutical Chemistry, Semmelweis University, Budapest, 1085 Hungary.|Research Group of Drugs of Abuse and Doping Agents, Hungarian Academy of Sciences Budapest, 1051 Hungary.
authors.forename: Máté
authors.initials: M
authors.lastname: Somlyay
authors.affiliation: Department of Pharmaceutical Chemistry, Semmelweis University, Budapest, 1085 Hungary.|Research Group of Drugs of Abuse and Doping Agents, Hungarian Academy of Sciences Budapest, 1051 Hungary.
authors.forename: Béla
authors.initials: B
authors.lastname: Noszál
mesh_terms: D000465:Algorithms; D003543:Cysteamine / Q000737:chemistry; D003545:Cysteine / Q000737:chemistry; D004220:Disulfides / Q000737:chemistry*; D005978:Glutathione / Q000737:chemistry; D006710:Homocysteine / Q000737:chemistry; D006863:Hydrogen-Ion Concentration; D008954:Models, Biological; D008956:Models, Chemical; D010084:Oxidation-Reduction; D066244:Proton Magnetic Resonance Spectroscopy; D011522:Protons; D012016:Reference Values; D012996:Solutions / Q000737:chemistry; D013438:Sulfhydryl Compounds / Q000737:chemistry*
chemical_list: D004220:Disulfides; D011522:Protons; D012996:Solutions; D013438:Sulfhydryl Compounds; D006710:Homocysteine; D003543:Cysteamine; D005978:Glutathione; D003545:Cysteine