Konformationsanalysen von Modell-Tripeptiden: Der Einfluss von alpha,alpha-disubstituierten alpha-Aminosäuren auf die Sekundärstruktur. Teil II. Röntgenstrukturanalyse und Konformationsenergie-Berechnungen

Abstract

Conformational Analysis of Tripeptide Models: The Influence of alpha,alpha-disubstituted alpha-Amino Acids on the Secondary Structure. X-Ray Analysis and Conformational Energy Calculations
The X-ray analysis of tripeptide Z-Ile-Val(2-Me)-benzocaine (1f) reveals the presence of a type-III beta-turn. Moreover, MMP2 calculations on tripeptides, e.g. Z-Ile-Aib-benzocaine (1c), Z-Ile-D-Val(2-Me)-benzocaine (1g), Z-Ile-Gly(2,2-Pr2)-benzocaine (1h), Z-Ile-Gly-benzocaine (1a), and 1f, fit well into the frame of NMR and CD investigations. They allow considerations on the relative stability of different types of beta-turns dependig on the peptide sequence, e.g. the kind of alpha,alpha-disubstituted amino-acid moieties.