Hexokinases have been isolated from the yeast cell in two distinct forms, designated P-I and P-II. These are separate, noninterconvertible isozymes. Hexokinase is used to determine glucose, fructose, mannose and ATP. Chromatographically purified. A lyophilized powder containing ~30% buffer/stabilizer. Phosphohexose isomerase, 6-phosphogluconate dehydrogenase, adenylate kinase and creatine phosphokinase contaminant activities are 0.10%, 0.005%, 0.005% and 0.005%, respectively