Isolation of alcohol dehydrogenases from germinating seeds of pea, broad-bean, lentil and kidney-bean

The maximum of alcohol dehydrogenase (ADH) activity of germinating pea and broad-bean seeds sediments from 40 to 60% ammonium sulfate saturation, from lentil and kidney-bean seeds between 40 and 50%. This operation increased the specific activity of ADH preparations roughly tenfold. Chromatography on DEAE-eellulose and gel filtration increased the activity of the resulting preparation when compared with the initial preparation 178 times with pea, 334 times with broad-bean, 122 times with lentil and 77 times with kidney-bean. The ADHs resemble each other in coenzyme specificity: the reaction rate with NAD is one hundred times greater than with NADP. The substrate specificity is quite wide: besides ethanol, these enzymes oxidize 2-propene-l-ol (actually faster than ethanol), 2-butene-l-ol (at the rate of one half t h a t of ethanol) and butanol (even more slowly). In general, saturated alcohol analogues are oxidized more slowly than unsaturated ones. Methanol is a substrate for the enzym from pea only. The ADHs of the plants studied did not oxidize diols, sugar alcohols and cyclic alcohols. The enzyme from pea has the widest substrate specificity oxidizing isobutanol, phenylalcohol and mercaptoethanol. ADHs, which are widely encountered in plants, resemble each other to a certain degree — they have identical coenzymes, equal Km values and equal values of the pH optimum, they differ in the purification process and in substrate specificity.