Specific Ion Effects on the Enzymatic Activity of Alcohol Dehydrogenase from Saccharomyces Cerevisiae

The enzymatic activity of alcohol dehydrogenase (ADH) in the presence of a range of electrolytes is investigated. In the pres-ence of 150 and 200 mM cations a substantial increase in activity following the series GnCl no salt > NaClO4 > NaSCN with a peak in activity increase of 75% in the presence of NaBr. The values of the Micaelis-Menten constant (Km) did not show any significant ion specific effect, while the maximum rate (Vmax) of ethanol oxidation to acetaldehyde was strongly ion specific. The changes in specific activity and Vmax in the presence of anions likely arises from ion specific interactions with charged residues in the active site of ADH. The data indicate that the enzymatic activity of alcohol dehydrogenase can be modulated by the nature of electrolytes at physiological concentration.