CATALASE FROM COMAMONAS COMPRANSORIS

Abstract

The aerobic carbon monoxide-oxidizing bacterium Comamonas compransoris is noticeable by containing a low molecular weight catalase with hyperbolic substrate saturation kinetics and high specific activity. The catalase has been purified from extracts of pyruvate-grown cells. The molecular weight is 150, 000, it consists of two identical subunits of 75, 000. The isoelectric point is 4.86. The absorption spectra of the native enzyme and of the reduced pyridine hematochrome resemble the corresponding spectra of bovine liver catalase. The catalase from Comamonas compransoris apparently contains two heme IX-groups per molecule. The substrate (H₂O₂)-saturation curve shows Michaelis-Menten kinetics with a K_m of 1.93mM and a turn-over number of 1.4× 10⁶/min. The pH optimum is 6.5, the dependence on temperature is weak. Imidazole increases the catalatic activity. The catalase peroxidizes pyrogallol, catechol and guajacol. In an open system with continuous substrate flow the enzyme is quickly inactivated.