Ascorbic acid oxidase and

A number of enzymes have been characterized that catalyze reactions involving DHA. In addition, other aspects of DHA biochemistry can be deduced from metabolic studies of ascorbic acid. Experiments demonstrating the biological oxidation of AA and reduction of DHA were first made in 1928 (10) and during the next decade several groups studied these reactions. By 1941 Crook (62) was able to separate the ascorbic acid oxidase and DHA reductase activities and to show that glutathione was used in the reductase reaction. 

D17. Dodds, M. L., Comparative substrate specificity studies of ascorbic acid oxidase and copper ion catalysis. Arch. Biochem. 18, 51-58 (1948),... 

Ascorbic acid in presence of ascorbic acid oxidase and dehydroascorbic acid reductase... 

Ascorbic acid oxidase oxidizes ascorbic acid to dehydroascorbic acid. In a pumpkin, two His, Cys and Met coordinate to type I copper, two His and OH (or H2O) to type II copper, and three His to each two type III copper (Fig. 2-24) [46]. Type II and Type III coppers form a triangular cluster, which presumably plays an important role in the four electron reduction of O2. Ascorbic acid oxidase and laccase have similar structures composed of three domains, but celluloplasmin is composed of six domains. 

White, G. a., and R. M. Krupka Ascorbic Acid Oxidase and Ascorbic Acid Oxygenase of Myrothecium verrucaria. Arch. Biochem. Biophys. 110, 448 (1965). 

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