Stereochemistry of porphyrinogen carboxy-lyase reaction in haem biosynthesis

Abstract

Stereospecifically deuteriated and tritiated succinate was incorporated into the acetate residues of uroporphyrinogen III which on decarboxylation generated asymmetric methyl groups in coproporphyrinogen III and then in haem; degradation of the latter yielded chiral acetate deriving from the C and D rings of haem and configurational analysis of this derived acetate shows that the carboxy-lyase reaction proceeds with a retention of configuration.