抄録
1. The enzyme catalyzing the reversible oxidation of 3-OH-MHB to 3-keto-MHB is located in the soluble fraction of rabbit liver.
2. NAD+ and NADP+ can function equally well as hydrogen acceptors to this enzyme.
3. It seems that coenzymes are rather firmly bound to the enzyme.
4. This enzyme is inhibited by p-chloromercuribenzoate, α, α'-dipyridyl or o-phenanthroline.
5. Pyridine nucleotides-dependent 3-OH-MHB oxidizing enzyme is activated by FAD, FMN, methylene blue, ferricyanide and menadione, and by the disulfide compounds such as glutathione (oxidized), cystine and α-lipoic acid in the presence of pyridine nucleotide, and postulate that these compounds play the role of secondary hydrogen acceptor in this enzyme system reaction.
6. The partially purified enzyme also catalyzes the reduction of 3-keto-MHB to 3-OH-MHB in the presence of NADH or NADPH.
The authors are indebted to Wakamoto Pharmaceutical Co. Ltd. for their supply of FAD and FMN. This work was supported partly by a Grant in Aid for Scientific Research provided by the Ministry of Education to which author's thanks are also due.
