A no. of peptides were synthesized from the carboxyl component containing a free side chain carboxyl group of aspartyl or glutamyl residue through thermolysin catalysis. The effects of neighboring residues situated closely to a C-terminal glutamic or aspartic acid in the carboxyl component on the formation of peptide bond were studied. The efficiency of coupling by thermolysin varied with the nature of the amino component and the carboxyl component. Strict stereospecificity was observed

Key words: AMINO ACID, CONDENSATION REACTION, GLUTAMIC ACID, ASPARTIC ACID, PEPTIDE, CARBOXY GROUP, ENZYMATIC, THERMOPHILIC BACTERIA