OXIDATION-REDUCTION POTENTIALS OF THIOL-DISULFIDE SYSTEMS

Abstract

THIOL-DISULFIDE SYSTEMSferric or cupric ions.They believed that this result disproved the mechanism that Dixon had advanced.Michaelis and Flexner (7) confirmed the electrode equation deduced by Dixon and Quastel, and showed that all the proposed explanations were inadequate.Barron, Flexner, and Michaelis ( 8) suggested that the cysteine potential at the mercury electrode is due to the following reaction.(RS),Hg + 2H+ + 2e-z$ 2RSH + Hg Under fixed experimental conditions, they said, the concentration of mercuric cysteinate remains constant and is unaffected by the ratio of thiol to disulfide or the pH.They presented little quantitative evidence for this theory, but they did show that metallic mercury is attacked by cysteine to form slightly soluble complexes.Williams and Drissen (9) and Fischer (10) attempted to solve the problem by potentiometric titration of the reduced form.They obtained different Eo values with different oxidizing agents.In the case of titra-