Synthesis of peptides analogous to the N-terminal eicosapeptide sequence of ribonuclease A. Part III. A new synthesis of the C-terminal octapeptide 13–20

Abstract

Synthesis is described of the octapeptide corresponding to the 13–20 sequence of the bovine pancreatic ribonuclease A. The pentapeptidebenzyloxycarbonyl-L-seryl-L-threonyl-L-seryl-L-alanyl-L-alanine t-butyl ester was built up by coupling, by the azide procedure, benzyloxycarbonyl-L-seryl-L-threonine hydrazide with L-seryl-L-alanyl-L-alanine t-butyl ester.

The subsequent elongation to the octapeptide was carried out stepwise by the p-nitrophenyl ester method. Exposure of the protected peptide to trifluoroacetic acid yielded L-methionyl-L-aspartyl-L-seryl-L-seryl-L-threonyl-L-seryl-L-alanyl-L-alanine.