title: Species-Specific Standard Redox Potential of Thiol-Disulfide Systems: A Key Parameter to Develop Agents against Oxidative Stress.
abstract: Microscopic standard redox potential, a new physico-chemical parameter was introduced and determined to quantify thiol-disulfide equilibria of biological significance. The highly composite, codependent acid-base and redox equilibria of thiols could so far be converted into pH-dependent, apparent redox potentials (E'°) only. Since the formation of stable metal-thiolate complexes precludes the direct thiol-disulfide redox potential measurements by usual electrochemical techniques, an indirect method had to be elaborated. In this work, the species-specific, pH-independent standard redox potentials of glutathione were determined primarily by comparing it to 1-methylnicotinamide, the simplest NAD+analogue. Secondarily, the species-specific standard redox potentials of the two-electron redox transitions of cysteamine, cysteine, homocysteine, penicillamine, and ovothiol were determined using their microscopic redox equilibrium constants with glutathione. The 30 different, microscopic standard redox potential 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, Hungary.
authors.forename: Arash
authors.initials: A
authors.lastname: Mirzahosseini
authors.affiliation: Research Group of Drugs of Abuse and Doping Agents, Hungarian Academy of Sciences, Hungary.
authors.forename: Béla
authors.initials: B
authors.lastname: Noszál
mesh_terms: D004220:Disulfides / Q000378:metabolism*; D005978:Glutathione / Q000378:metabolism; D006863:Hydrogen-Ion Concentration; D010084:Oxidation-Reduction; D018384:Oxidative Stress; D066244:Proton Magnetic Resonance Spectroscopy; D011522:Protons; D013045:Species Specificity; D013438:Sulfhydryl Compounds / Q000378:metabolism*
chemical_list: D004220:Disulfides; D011522:Protons; D013438:Sulfhydryl Compounds; D005978:Glutathione