Properties of glucose dehydrogenase from vegetative cells of Bacillus subtilis and effect of dipicolinic acid and its chemical analogues on the enzyme.

Abstract

The glucose dehydrogenase from vegetative cells of Bacillus subtilis PCI 219 strain was partially purified through two ammonium sulfate fractionations and a filtration on Sephadex G-200. The optimal pH for stability of this enzyme was 6.0 and the optimal pH for the reaction catalyzed was 6.8. The Michaelis constant for glucose was 5.1×10−3 M at pH 6.8. High concentrations of lutidinic acid and isocinchomeronic acid remarkably protected the enzyme from heat inactivation, while dipicolinic acid showed a moderate protecting effect. Other chemical analogues of dipicolinic acid, such as quinolinic acid, nicotinic acid and isonicotinic acid, had less effect than dipicolinic acid, and phthalic acid had no effect. These effects of dipicolinic acid and other chemicals on the activity of glucose dehydrogenase from the vegetative cells were same with those on the activity of glucose dehydrogenase from the spores.