Secondary alcohol dehydrogenase from a vinyl alcohol oligomer-degrading Geotrichum fermentans; stabilization with Triton X-100 and activity toward polymers with polymerization degrees less than 20

Abstract

An NAD+-dependent secondary alcohol dehydrogenase has been found in the cells of Geotrichum fermentans WF9101 grown on 2,4-pentanediol (the constitutional unit of vinyl alcohol polymers). Although the enzyme was unstable and lost its activity very rapidly, we found that it could be purified after stabilization in a buffer containing 0.01% Triton X-100. The molecular weight of the purified enzyme was 88,000 with subunit size of molecular weight 42,000. The enzyme, which was specific for the (S)-(+)-enantiomers, was active on various secondary mono-ols and diols, notably, 2-hexanol. The K_m values at 30 °C, pH 8.0, were 240 μm for 2-hexanol and 48.7 μm for NAD⁺. This enzyme showed activity toward vinyl alcohol polymers with average degrees of polymerization of less than 20, and was assumed to contribute on the degradation of poly(vinyl alcohol) in synergism with other microorganisms.