Human proinsulin, IV[1--3]: synthesis of a protected peptide fragment corresponding to the sequence 1--23 of the prohormone.

The synthesis of the protected peptide fragment: Boc-Phe-Val-Asn-Gln-His-Leu-Cys-(Trt)-Gly-Ser(But)-His-Leu-Val-Glu(OBut)-Ala-Le u-Tyr(But)-Leu-Val-Cys(Trt)-Gly-Glu(OBut)-Arg(HCl)-Gly-OH, corresponding to the sequence 1--23 of human proinsulin (sequence 1--23 of human insulin B chain) is described. The fragment was synthesized from two intermediate fragments: 1--16 and 17--23 and was purified by gel filtrationon Sephadex LH-20 in dimethylformamide.