Paul, PKC and Sukumar, M and Bardi, R and Piazzesi, AM and Valle, G and Toniolo, C and Balaram, Padmanabhan (1986) Stereochemically constrained peptides. Theoretical and experimental studies on the conformations of peptides containing 1-aminocyclohexane carboxylic acid. In: journal of the American chemical Society, 108 (20). pp. 6363-6370.
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Conformational energy calculations on the model system N-acetyl- 1 -aminocyclohexanecarboxylic acid N'methylamide (Ac-Acc6-NHMe), using an average geometry derived from 13 crystallographic observations, establish that the Acc6 residue is constrained to adopt conformations in the helical regions of In contrast, the a,a-dialkylated residue with linear hydrocarbon side chains, a,a-di-n-propylglycine favors fully extended backbone structures (6 1= $ = 180'). The crystal structures of two model peptides, Boc-(Acc6),-OMe (type 111 @-turn at -Acc6(1)-Acc6(2)-) and Boc-Pro-Acc6-Ala-OMe (type I1 P-turn at -Pro-Acc6-), establish that Acc6 residues can occupy either position of type 111 P-turns and the i + 2 position of type I1 @-turns. The stereochemical rigidity of these peptides is demonstrated in solution by NMR studies, which establish the presence of one intramolecular hydrogen bond in each peptide in CDCI, and (CDJ2S0. Nuclear Overhauser effects permit characterization of the @-turn conformations in solution and establish their similarity to the solid-state structures. The implications for the use of Acc6 residues in conformational design are considered.
|Item Type:||Journal Article|
|Additional Information:||Copyright of this article belongs to American Chemical Society.|
|Department/Centre:||Division of Biological Sciences > Molecular Biophysics Unit|
|Date Deposited:||09 Nov 2010 07:50|
|Last Modified:||09 Nov 2010 07:50|
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