Partial purification and characterization of an alcohol dehydrogenase of Mycobacterium tuberculosis var. bovis (BCG).

An alcohol dehydrogenase of broad specificity was purified 43-fold from extracts of Mycobacterium tuberculosis var. bovis (BCG) grown on Sauton medium. It was also present in cells grown in Dubos medium and Tween 80 and bovine serum albumin. The enzyme, which appeared to be soluble, acted as an oxidoreductase in the system butan-1-ol-NADP. It was eluted from Sephadex G-200, hydroxylapatite and DEAE-cellulose in a single peak. The molecular weight, as determined by gel filtration on Sephadex G-200, was about 75,000. Results of electrophoresis in sodium dodecyl sulphate-polyacrylamide gels were compatible with the existence of two subunits each of molecular weight 37,500. The optimum pH was about 8.5 when the enzyme catalysed the oxidation of butan-1-ol, and about 8.2 for the reverse reaction. The apparent Km was 0.125 mM for butyraldehyde and 0.22 M for butan-1-ol. The dehydrogenase activity was maintained after heat treatment (40 min at 55 degrees C) in the presence of 30% (W/V) glycerol, but was abolished by heating (40 min at 55 degrees C) in the presence of 0.1 M-EDTA. The activity of enzyme inactivated by heat and EDTA could be fully restored at room temperature in the presence of 2 mM-Zn2+.