Institution: | Biopolymer Research Center, CNR, Department of Organic Chemistry, University of Padua, 35131, Padua, Italy Department of Chemistry, University of Naples, 80134, Naples, Italy The Institute of Chemistry, University of Basilicata, 85100, Potenza, Italy |
Abstract: | Conformational energy computations on the 1-aminocyclopropane-1-carboxylic acid mono-, di-, and tripeptide amides, (Ac-(Ac3c)n---NHMe (n=1−3), indicate that this C , -dialkylated, cyclic -amino acid residue is conformally restricted and that type-I(I′) β-bends and distorted 310-helices are particularly stable conformations for the di- and tripeptide amides, respectively. The results of the theoretical analysis are in agreement with those obtained in an i.r. absorption and 1H n.m.r. investigation in chloroform solution of A.c.3c-rich tri- and tetrapeptide esters. A comparisons is also made with the conclusions extracted from our previous work on peptides rich in Aib ( -aminoisobutyric acid), Ac5c(1-aminocyclopentane-1-carboxylic acid), and Ac6c (1-aminocyclohexane-1-carboxylic acid). |