The Preparation of Yeast Hexokinases

Publisher Website
Google Scholar
Abstract
Improved methods are described for the preparation of hexokinase from baker's yeast. The isolation procedure is designed to avoid proteolysis, by using mechanical disintegration of the yeast cells, by organophosphate inhibition of the serine-dependent proteases, and by removal of all other proteases by gel filtration. Three isoenzymes, A, B and C, can be obtained thus. For hexokinase A, the ratio of activity in phosphorylating fructose as compared to glucose is about twice that of B or C. Hexokinase C is very similar in properties to B, but is separable by ion-exchange chromatography and appears to be a conformational isoenzyme of B. In the final purified state, the specific activity on glucose (27 mM, pH 8.3, 25.0) is 275 international units per mg for A, 900 for B and 750 for C, these values being higher than those for previously reported forms.