Rice cells in suspension culture had high alcohol dehydrogenase activity during the logarithmic growth phase (3rd to 5th day). Ethanol was accumulated both in the cells and in the medium. The highest amount of ethanol was accumulated on the 4th day in cells (10μmoles/g fresh weight) and during the stationary growth phase (8th day) (180 mM, ca. 1%) in the medium. The enzyme was isolated from the cell extract and purified 36-fold with a 14%yield by ammonium sulfate fractional precipitation, and chromatography on DEAE-Sephadex, Sephadex G-150 and Blue Dextran-Sepharose. The purified enzyme was homogeneous, as judged by its sedimentation velocity, and poly acrylamide gel, starch gel and SDS-polyacrylamide gel electrophoreses. Its molecular weight was 76,000 distributed in two, identical 37,000 subunits. The isoelectric point was at pH 5.5. The enzyme contained 2.1 g atoms of zinc, 12 free SH groups and 3 to 4 SS bonds per molecule. The pH optimum for ethanol oxidatioa was pH 9.5 and for acetaldehyde reduction pH 6.0. TheKmvalues for ethanol, NAD$, acetaldehyde and NADH were 64.5 mM, 47.1μM, 1.3 mM and 9.5μM. The amino acid composition, substrate specificity, and the effects of chelators, SH reagents and sugar metabolic intermediates also are report
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