Intracellular Substrates of a Heme-Containing Ascorbate Oxidase in Pleurotus ostreatus

摘要

A novel heme-containing ascorbate oxidase isolated from oyster mushroom, Pleurotus ostreatus, catalyzesoxidation of ascorbic acid (Kim et al., 1996). In this report, we describe the identification of intracellularsubstrates of the enzyme in the mushroom. Six compounds, which can serve as substrate of the heme-con-taining ascorbate oxidase, were identified as L-ascorbic acid, D-erythroascorbic acid, 5-0-(a-D-glucopyr-anosyl)-D-erythroascorbic acid, 5-0-(a-D-xylopyranosyl)-D-erythroascorbic acid, 5-methyl-5-0-(a-D-gluco-pyranosyl)-D-erythroascorbic acid, and 5-methyl-5-0-(a-D-xylopyranosyl)-D-erythroascorbic acid. All of thecompounds were oxidized at a significant rate by the heme-containing ascorbate oxidase. Oxidation of thecompounds produced equimolar amounts of hydrogen peroxide per mole of substrate.