Synthesis of sequential oligopeptides and polypeptide having the sequence of L ‐alanyl‐ L ‐leucylglycine

A series of sequential oligopeptides having simple nonpolar side chains, Nps‐(L‐Ala‐L‐Leu‐Gly)n‐ OEt has been prepared by a stepwise fragment‐condensation method using Nps‐L‐alanyl‐L‐leucylglycine N‐hydroxysuccinimide ester, which was prepared by the Nps‐N‐carboxy α‐amino‐acid‐anhydride method. The success of the synthesis of the peptide having a high‐molecular weight, such as octadecapeptide, results from the highest solubility of the tripeptide unit, L‐alanyl‐L‐leucylglycine. The sequential polypeptide having the same tripeptide sequence was also prepared by polycondensation of the tripeptide N‐hydroxy‐succinimide ester.