Glycine Metabolism by Rat Liver Mitochondria: III. The Glycine Cleavage and the Exchange of Carboxyl Carbon of Glycine with Bicarbonate*

Abstract

Extracts of acetone powder of rat liver mitochondria catalyzed the cleavage of glycine, giving rise to the formation of 1 molecule each of serine, CO₂ and NH₃ from 2 molecules of glycine. The glycine cleavage required the addition of THF. Significant decarboxylation of glycine occurred only aerobically. The extracts also catalyzed the exchange of the carboxyl carbon of glycine with CO₂. The exchange activity was greatly suppressed by the addition of THF. The reaction could proceed either aerobically or anaerobically, but a suitable balance of the oxidation-reduction state appeared to be required for the smooth operation of the exchange reaction. The exchange reaction represents apparently a partial reaction of the glycine cleavage reaction and a pyridoxal phosphate enzyme plays a central role in these reactions.