KINETICS OF ASCORBIC ACID OXIDATION CATALYSED BY Cu(Ⅱ)-GLYCINE COMPLEX

The kinetics of L-ascorbic acid (H₂A) oxidation catalysed by Cu (Ⅱ)-glycine (Gly) complex was studied in phosphate buffer (7.1) at 11～25℃. The rate of Cu-Gly catalysed reaction conformed to the Michaelis-Menten equation with respect to ascorbate. H₂O₂ was produced during this reaction. Cu(Ⅱ) did not change its valence when O₂ was saturated. The initial rate of the catalytic reaction decreased in the order: Cu-Gly >Cu-glycylglycylglycine> Cu-glycylglycine. The electron spin resonance spectrums of the catalyst solutions were changed by adding H₂A. A mechanism via a ternary complex (HA~-…Cu-Gly…O₂) was proposed.