Substrate Specificity of the Myrothecium Ascorbic Acid Oxidase

Abstract

THE substrate specificity of the copper-containing ascorbic acid oxidase of higher plants was studied principally by Zilva et al. 1,2. More recently, Mandels3,4 discovered an ascorbic acid oxidase in spores of Myrothecium verrucaria (Alb. and Schw.) Ditm. ex Fr. which was termed ‘atypical’ chiefly because it differed from the classical copper-enzyme in substrate specificity and in its resistance to metal enzyme inhibitors. It did not oxidize D-glucoascorbate or D-araboascorbate, and the latter inhibited oxidation of L-ascorbate. The mycelium of M. verrucaria also contains an atypical ascorbic acid oxidase, but with properties distinctly different from those of the spore-enzyme as well as of the copper-enzyme5. This communication describes the differences in substrate specificities.