Asparagusate dehydrogenases and lipoyl dehydrogenase from asparagus mitochondria

1. Lipoyl dehydrogenase (NADH: lipoamide oxidoreductase, ED 1.6.4.3) and two asparagusate dehydrogenases from asparagus mitochondria were purified by a series of steps, freezing and thawing, sodium dodecylsulfate extraction, and chromatography on Sephadex G-200 and DEAE-cellulose. 2. Lipoyl dehydrogenase was highly specific for alpha-lipoic acid, which could not be replaced at all by asparagusic acid. Each of the asparagusate dehydrogenases was capable of reducing both asparagusic and alpha-lipoic acids by using NADH as hydrogen donor. 3. Reduction of alpha-lipoic cid with NADH by lipoyl dehydrogenase was activated by NAD, but that of asparagusic acid by asparagusate dehydrogenase was inactivated by NAD. 4. Lipoyl dehydrogenase and two asparagusate dehydrogenases differed in electrophoretic mobility on polyacrylamide gels.