Separation and properties of polyhydric alcohol dehydrogenases from Mycobacterium sp. 279 and Mycobacterium phlei

Glucose- or polyol-grown mycobacteria were disrupted by ultrasonication and cell-free extracts fractionated with ammonium sulfate, Sephadex G-100 and DEAE-cellulose chromatography. In various enzyme preparations, NAD-coupled polyol dehydrogenase activities were determined spectrophotometrically at 340 nm. Evidence is presented forthe occurrence of three types of enzymes called after the most active substrates: ribitol dehydrogenase, D-arabitol dehydrogenase and D-sorbitol dehydrogenase. The enzymes have been separated, and characterized on the basis of their polyol specificity, molecular weight, heat resistance and pH stability. The dehydrogenation reaction was influenced by the kind of buffer and proceeded most rapidly with glycine/NaOH in a range of pH from about 9 (for glycerol, erythritol, and ribitol) to about 11 (for other polyols). Tris buffer was found to inhibit the reaction with polyhydric alcohols containing D-ribo or D-xylo configuration. Km values for several polyols and Ki for Tris have been established.