Purification and Characterization of the Secondary Alcohol Dehydrogenase from Propane-utilizing Mycobacterium vaccae Strain JOB-5

Mycobacterium vaccae strain JOB-5 cultured in the presence of propane contained an inducible secondary alcohol dehydrogenase. The enzyme was purified 198-fold using DEAE-cellulose, omega-aminopentyl agarose and NAD-agarose chromatography. The Mr of the enzyme was approximately 136000, with subunits of Mr 37000. The pH optimum for the reaction oxidizing propan-2-ol to propanone was 10-10.5 while the optimum for the reverse reaction was 7.5-8.5. The isoelectric point was 4.9. NAD but not NADP could serve as electron acceptor. The apparent Km values for propan-2-ol and NAD were 4.9 X 10(-5)M and 2.8 X 10(-4)M, respectively. The enzyme was inhibited by thiol reagents and metal chelators. It appears to play an essential role in the metabolism of propane by this bacterium.