THE REGIONAL DISTRIBUTION OF d-GLYCERATE DEHYDROGENASE AND 3-PHOSPHOGLYCERATE DEHYDROGENASE IN THE CAT CENTRAL NERVOUS SYSTEM: CORRELATION WITH GLYCINE LEVELS

The activities of d -glycerate dehydrogenase, 3-phosphoglycerate dehydrogenase and lactate dehydrogenase have been measured in high-speed supernatant fractions from different regions of the cat CNS. Only d -glycerate dehydrogenase showed any significant regional variation in levels of activity, and this regional distribution correlated well with the regional distribution of glycine. In view of the previous finding that glycine inhibits d -glycerate dehydrogenase of rat cortex in a non-competitive manner suggesting endproduct inhibition (Uhr and Sneddon , 1971) this correlation is considered additional evidence to suggest that d -glycerate may be an important source of glycine in the CNS.