Verdoppelungserscheinungen beim Ringschluss Von Peptiden. V. Relative Bedeutung der sterischen Hinderung und der Assoziation über Wasserstoff‐Brücken bei Tripeptiden. Spektroskopische Versuche zur Konformationsbestimmung. 12. Mitteilung über homodet cyclische Polypeptide

Abstract

Abstract Various factors inducing the doubling reaction during cyclization of small peptides are reviewed. To test their relative importance, derivatives of the tripeptide, Gly‐Pro‐Gly, and of the monodepsi‐dipeptide, glycyl‐glykolyl‐glycyl, have been subjected to cyclization : both undergo the doubling reaction to give cyclo‐glycyl‐ L ‐prolyl‐glycyl‐glycyl‐ L ‐prolyl‐glycyl and cyclo‐glycyl‐glykolyl‐glycyl‐glycyl‐glykolyl‐glycyl respectively. The «monomers» of this doubling reaction obviously cannot associate via H‐bridges according to Fig. 1 during the reaction, an association according to Fig. 12 could, however, be envisaged as working hypothesis. Steric hindrance seems to play an eminent rôle in the cyclization of tripeptides to cyclo‐hexapeptides.