Abstract
As preparatory studies of the kinetics on carboxylase catalysis, partial purification of apocarboxylase and some properties of the enzymatic reaction were investigated. Apocarboxylase solution obtained from bakers' yeast by repeated extractions with 0.05M Na-phosphate buffer was purified to approximately 120-fold by gel-filtration with Sephadex G-25 and by column-chromatographic separation with DEAE-cellulose. The purified enzyme was tinged with pale yellow, and showed the specific absorption-bands at 405mμ and 278mμ. The enzymatic reaction took place only when the two cofactors, cocarboxylase and Mg^<2+>, was added in the reaction mixture. Mg^<2+> and cocarboxylase combined with apocarboxylase directly, and they were increased the affinities for apoenzyme by each other. The enzymatic reaction was remarkablly affected by ionic strength of medium. So that it was observed that the inhibitory effect of ions was caused by substrate.
