Enzymic delactonization of dehydro-l-ascorbate in animal tissues

Studies on Dehydroascorbic Acid Reductase in Escherichia Colik12

“…The delactonization of dehydroascorbic acid proceeds by an enzymatic reaction in animal tissues (10)(11), and dehydroascorbic acid delactonizing enzyme was reported to be identical to lactonase I (aldonolactonase, gluconolactonase) (11)(12). The gluconolactonase was found by Brodie and Lipmann (14) in bacteria.…”

“…On the other hand, E. coli (3)(4) and St. albus (2) possess a high activity of reducing dehydroascorbic acid, protecting the decomposition of ascorbic acid. In animals, dehydroascorbic acid is enzymatically delactonized to 2, 3-diketogulonic acid, which cannot become dehy droascorbic acid by the reverse reaction (11)(12). Therefore, 2, 3-diketogulonic acid lacks the antiscorbutic activity, whereas dehydroascorbic acid possesses the activity, and what is eliminated in the urine following excessive administration is not dehy droascorbic acid, but ascorbic acid (18).…”

“…Contamination of Other Enzymes in the Preparation Glyoxalase I activity was observed in the initial extract of E, coli but not observed in the purified enzyme, showing that the enzyme was different from glyoxalase I. The activity of gluconolactonase, which is known to delactonize dehydroascorbic acid (11)(12)(13), was observed in the initial extract of E. coli, but not observed in the purified enzyme.…”

Reduction of Dehydroascorbic Acid With Pyruvate Oxidase System

“…Kagawa et al reported that delactonization of dehydroascorbic acid proceeded by an enzymatic reaction in animal tissues (14)(15) , and dehydro ascorbic acid-delactonizing enzyme was identical to lactonase I (aldonolactonase, gluconolactonase) (16). The gluconolactonase was found by Brodie and Lipmann (17) in bacteria.…”

Reduction of Dehydroascorbic Acid With Pyruvate Oxidase System

“…As dehydroascorbic acid is delactonized by the enzymatic reaction in animal tissues (2)(3), the presence of the mechanism of reducing dehydroascorbic acid into ascorbic acid in animal tissues might be desirable .…”