Glycine Metabolism: I. PROPERTIES OF THE SYSTEM CATALYZING THE EXCHANGE OF BICARBONATE WITH THE CARBOXYL GROUP OF GLYCINE IN PEPTOCOCCUS GLYCINOPHILUS

Abstract

Abstract Extensive purification of the enzyme system from Peptococcus glycinophilus catalyzing the labilization of the glycine carboxyl group has been accomplished, and some reaction properties of the purified system have been defined. Two protein fractions essential for the exchange of the glycine carboxyl group with bicarbonate were isolated. Each of the proteins was totally inactive by itself in catalyzing the exchange, but combination of the two fractions resulted in high activity. One of the proteins, purified 60-fold, was shown to be a pyridoxal phosphate-containing enzyme and was destroyed by boiling. The other protein, purified 230-fold, was colorless and stable to boiling in 5% ammonium sulfate. Maximal CO2 exchange activity was observed at pH 7.0, required the addition of 10-2 m sulfhydryl groups, and proceeded more rapidly in the presence of 1 mm ethylenediaminetetraacetate than in its absence. The reaction was inhibited by formaldehyde, glyoxylate, p-chloromercuribenzoate, and mercury and copper ions; but it was neither inhibited by avidin nor stimulated by biotin or numerous divalent metals. Glyoxylate and glycolate failed to react in the system which allowed the exchange of bicarbonate with the carboxyl group of glycine.