SYNTHESIS AND PROPERTIES OF HIGH-MOLECULAR-WEIGHT POLYPEPTIDES CONTAINING PROLINE

High-purity N-carboxy-L-proline anhydride (N-carboxy-2-pyrrolidinecarb oxylic acid anhydride) was synthesized. We used triethylamine instead of expensive Ag2O to remove HCl during the synthesis. Copolypeptides w ith a random sequence of L-proline (Pro) with glycine, L-alanine (Ala) , L-alpha-aminobuthyric acid (Abu), L-Norvaline (Nva) or L-leucine (Le u) were synthesized by copolymerization of the corresponding N-carboxy -alpha-amino acid anhydrides in solution. Copolypeptides of Pro with A la or Abu were partially soluble in water. However, the copolypeptides of proline with Nva or Leu with longer side chains were insoluble in water. The conformation of water-soluble copolymer at various pH was a nalyzed by circular dichroism (CD). The structures of the polypeptides in aqueous solution were almost independent of the pH, and were in a collagen-like conformation.