In order to examine the requirement for the formation of β-conformation in the course of nascent polymerization step and tile critical length of f-conformation, the peptides containing glycine, L-valine and L-isoleocine were synthesized by heterogeneous polymerization of their α-amino acid N-carboxy anhydrides (NCA) in acetonitrile with n-butylamine as an initiator and the poly-L-alanine were polymerized by those oi active oligtopeptides. The polymerization of L-alanine NCA were carried out by the oligoglycine, oligo-L-valise and oligo-L-isoleucine which were in β-conformation as initiator. The helical α-poly-L-alanine could be formed rather than forming the β-poly-L-alanine, and the critical length of β-oligopeptides were found to be about eight of degree of polymerization.

α-아미노산무수물의 중합과정에서 β-구조형성의 필연성과 그의 임계쇄장을 알기 위하여 아세토리트릴중에서 1차아민인 n-부틸아민을 개시제로 glycine, L-valine 및 L-isoleucine 의 oligopeptide를 합성하고 다시 이것을 개시제로 하여 L-alanine NCA를 중합하였다. β-구조를 가지고 있는 oligoglycine, oligo-L-valine 및 oligo-L-isoleucine을 개시제로 L-alanine NCA를 불균일계로 중합하여 결정성장기구를 검토한 결과 β-poly-L-alanine의 형성없이 α-helical conformation을 가진 poly-L-alanine이 형성됨을 확인하였다. 이때의 β-oligopeptide들의 님계쇄장은 중합도가 약 8 정도였다.

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