Multiplicity and control of alcohol dehydrogenase isozymes in various strains of wine yeasts

Abstract

The control of formation of alcohol dehydrogenase (ADH) (EC 1.1.1.1) isozymes and their activity toward some of the higher alcohols (n-propanol, isobutanol, isopentanol, and active pentanol) was studied in ten different wine yeast strains under various physiological conditions of growth. Multiple forms of ADH were demonstrated by starch gel electrophoresis in all the strains. When grown anaerobically on glucose or under vinification conditions, the cells of most strains had a single isozyme band for ADH I. However, during aerobic growth on glucose or on ethanol, 2 to 4 additional bands were observed for ADH II and ADH III. With the higher alcohols as substrates, only ADH I bands were evident in all strains under anaerobic or vinification conditions. In glucose derepressed and aerobically grown cultures, ADH II and ADH III bands were also found with the higher alcohols as enzyme substrates. The increases in numbers of isozymes in derepressed or aerobic cultures were reflected as increased specific ADH activities in cell-free extracts. The results suggest that multiplicity of ADH isozymes, and their control by glucose repression and aerobic induction, are common phenomena in yeast; and that only one enzyme, ADH I, is involved in the formation of higher alcohols during vinification.