A Stable Glucokinase from a Thermophilic Bacterium

I. Purification and Some Properties

Abstract

A glucokinase (EC 2.7.1.2) was purified from Bacillus stearothermophilus, a moderate thermophile. The native glucokinase, M_r about 68, 000, consists of two identical subunits. This enzyme is relatively temperature- and pH-stable, the optimal pH range for the enzymatic activity being within the stable pH range. It selectively catalyzes the phosphorylation of glucose rather than other kinds of hexoses. The K_m values were estimated to be 1×10^-4M for glucose and 0.5×10^-4M for ATP. It shows no ATPase activity. The high stability, high substrate specificity, low K_m values for glucose and ATP, and the lack of ATPase activity make this enzyme advantageous for use in clinical chemical analysis.