The specificity of enzymes adding amino acids in the synthesis of the peptidoglycan precursors of Corynebacterium poinsettiae and Corynebacterium insidiosum.

A soluble extract from Corynebacterium poinsettiae able to synthesize the nucleotide precursor of ite peptidoglycan was prepared. This extract contained all the enzymes necessary for the synthesis of the peptide side-chain. The spedificity of these enzymes was determined and compared with the specificity of similar enzymes extracted from the closely related Corynebacterium insidiosum. In both organsims, addition of the third amino acid of the peptide side-chain was specific for the amino acid and nucleotide dipeptide involved in peptidoglycan synthesis in the parent organism. L-Diaminobutyric acid, which is found as the acetyl derivative in the precursor nucleotide and in the completed peptidoglycan of C. insidiosum, was added as the free amino acid and not as the acetylated compound.