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, Mandels^3,4 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.