Studies on the Ascorbic Acid Synthesis in Animal Tissues with the Reconstructed Enzyme Systems

Abstract

1. The enzyme system consisting of L-gulonolactone dehydrogenase, TPN-L-hexonate dehydrogenase and lactonase-I was recon-structed, and the actual formation of L-ascorbic acid was observed from D-glucuronic acid and L-gulonic acid.
2. Under the condition tested the absence, of lactonase-I resulted in the failure to synthesize L-ascorbic acid, although the synthesis occurred from D-glucuronolactone or L-gulonolactone.
3. The addition of barbital to the reconstructed system inhibited the L-ascorbic acid .synthesis. Chloretone did not affect the system.
4. The enzyme system consisting of TPN-L-hexonate dehydrogenase and DPN-L-gulo-nate dehydrogenase produced L-xylulose from D-glucuronic acid.
5. With the addition of L-gulonolactone dehydrogenase and lactonase-I, human liver homogenates became capable of forming L-ascorbic acid from L-gulonic acid.