Abstract
Polyaminopolycarboxylic acid with at least two ligand nitrogens such as ethylenediaminetetraacetic acid accelerates the copper-catalyzed autoxidation of cysteine. The extent of acceleration of the reaction is related to the stability constant of the Cu (II) chelate of the polyaminopolycarboxylic acid. N-Hydroxyethylethylenediaminetriacetic acid, N-hydroxy-1, 3-diaminopropanetetraacetic acid and ethyleneglycol-bis-(β-aminoethylether) tetraacetic acid are the most potent accelerators and those chelating agents have the stability constants of approximately 1017.5. Addition of a sufficient excess of the chelating agent over cysteine retards the oxidation.
