Crystallization and properties of l-lactate oxidase from Mycobacterium smegmatis

Abstract

1. An original method was devised for purifying and crystallizing l-lactate oxidase from Mycobacterium smegmatis. 2. The crystalline enzyme exhibited a single protein component (S020,w 14·7s) in the ultracentrifuge and also on electrophoresis on cellulose acetate strips. 3. The enzyme has a typical flavoprotein spectrum, and it was confirmed that the prosthetic group is FMN. 4. Preliminary studies indicated that the molecular weight is in the range 300000–400000. Since the minimum molecular weight was found to be 50000±3000, it was concluded that l-lactate oxidase contains 6–8moles of flavine/mole. 5. Other properties of the enzyme reported include the substrate specificity, an apparent Km for l-lactate, the effect of several inhibitors on the enzyme activity and the pH–activity curve.