Reduction of dehydroascorbic acid by bacteria. 1. Reducing mechanisms of Escherichia coli

Publisher Website
Google Scholar
Abstract
Hydrogenase and formic, lactic, succinic, malic, ethanol, glucose and glycine dehydrogenases, with their substrates, can-act as H-donating mechanisms for dehydroascorbic acid (DHA) reduction by E. coli. Cell-free dehydrogenase prepns. will not reduce DHA, indicating that some essential factor or factors is absent from them. The factor is not replacable by methylene blue, pyocyanine, glutathione, coenzyme II, yeast extract boiled or unboiled whole yeast. The effect of hydrogendonator concn. on the rate of DHA reduction, as compared with the rate of methylene-blue reduction, indicates that the rate of H transfer may be greatly reduced in the DHA-reducing system. Growth on lactate or formate in place of glucose increases the hydrogenase activity, but decreases the DHA-reducing activity. When more than one H-donator is present, the rates of DHA reduction are not additive. The rate of reduction when formate, lacatate and H are present together is not as great as when glucose is present alone.