Synthesis of the C-terminal undeca- and protected docosapeptide of bovine insulin B-chain.

The synthesis of two C-terminal peptides of bovine insulin B-chain are described. Thus, insulin fragments (B9-30) and ( B20 -30) were synthesized using nitrobenzoylglycyl -poly-(oxyethylene) as the soluble support. 4-Carboxy-2-nitrobenzyl ester of Boc-alanine was coupled to glycyl-poly(oxyethylene) and the syntheses were continued employing symmetrical anhydrides of Boc-amino acids. The protected peptides were cleaved from the support by photolysis and were purified on silica gel and Sephadex LH-20. All the protecting groups of a sample of the undecapeptide were removed with liquid HF and the unprotected peptide was purified on CM-cellulose. The synthesized peptides were gas chromatographically tested for the racemization of the individual amino acids. The results indicated that no residue was significantly racemized .