NADP(+)-dependent D-arabinose dehydrogenase shows a limited contribution to erythroascorbic acid biosynthesis and oxidative stress resistance in Saccharomyces cerevisiae.

The molecular aspects and physiological significance of NADP(+)-dependent D-arabinose dehydrogenase (ARA), which is thought to function in the biosynthesis of an analog of ascorbic acid, D-erythroascorbic acid in yeasts, were examined. A large subunit of ARA, Ara1p produced in E. coli, was purified as a homodimer, some of which was degraded at the N-terminus.

NAD+-specific D-arabinose dehydrogenase and its contribution to erythroascorbic acid production in Saccharomyces cerevisiae.

Erythroascorbic acid (eAsA) is a five-carbon analog of ascorbic acid, and it is synthesized from D-arabinose by D-arabinose dehydrogenase (ARA) and D-arabinono-gamma-lactone oxidase. We found an NAD+-specific ARA activity which is operative under submillimolar level of d-arabinose in the extracts of Saccharomyces cerevisiae. The hypothetical protein encoded by YMR041c showed a significant homology to a l-galactose dehydrogenase which plays in plant ascorbic acid biosynthesis, and we named it as Ara2p.

Heterologous expression of dehydroascorbate reductase from rice and its application to determination of dehydroascorbate concentrations.

We constructed an expression vector for rice dehydroascorbate reductase (DHAR) (EC 1.8.5.

Photochemical properties of kynurenine pathway metabolites and indoleamines.

Photochemical damages to the biological system may occur through photodynamic action in the presence of photosensitive molecules. Photodynamic action contains the following processes; 1) photosensitisation and/or 2) electron transfer, in which singlet oxygen and superoxide radical production for each in the presence of oxygen molecules. We have studied those processes after the absorption of light by kynurenine pathway metabolites and indoleamine derivatives.

Gender-related differences in mouse hepatic ethanol metabolism.

The effect of an acute oral load of 2 g ethanol/kg body weight was studied in a group of male and female 10-wk-old C3H/HeNCrj (C3H/He) mice to investigate gender change throughout differences of the hepatic ethanol metabolism of mice. The following parameters were measured in the serum from 0 h to 3 h after the start of the experiment: ethanol, acetaldehyde, and acetate. Their concentrations in the serum in female mice tended to show lower levels than in male mice.