Serine Racemase from Oryza sativa L.: Identification of Enzyme Reaction Regulation Mechanism by Mg²⁺

Abstract

The serine racemase from Oryza sativa L. is a pyridoxyal 5’-phosphate containing enzyme that catalyzes a racemization and a dehydratation of serine. In this study, we constructed the high expression system of the serine racemase from Oryza sativa L. in Escherichia coli, and examined the effect of the metal ions on the activity. The serine racemase activity increased by addition of Mg²⁺ or Ca²⁺, while the dehydratase activity decreased by Mg²⁺ or Cu²⁺. The kinetic analysis showed that Mg²⁺ does not affect on the Vmax value of the racemase activity but decreases the Km value for L-serine. These results suggest that the serine racemase and dehydratase activities are regulated by Mg²⁺.