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Stereochemistry of \alpha-Aminoisobutyric Acid Peptides in Solution: Helical Conformations of Protected Decapeptides with Repeating Aib-L-Ala and Aib-L-Val Sequences

Vijayakumar, EKS and Balaram, P (1983) Stereochemistry of \alpha-Aminoisobutyric Acid Peptides in Solution: Helical Conformations of Protected Decapeptides with Repeating Aib-L-Ala and Aib-L-Val Sequences. In: Biopolymers, 22 (9). pp. 2133-2140.

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Abstract

The decapeptides $Boc-{(Aib-L-Ala)}_5-OMe$ and $Boc-{(Aib-L-Val)}_5-OMe$ have been studied by 270-MHz lH-nmr in $CD{Cl}_3$ and ${({CD}_3)}_2SO$ solutions. Intramolecular hydrogen-bonded NH groups have been delineated using the temperature and solvent dependence of the NH chemical shifts and differential broadening of the NH resonances, induced by addition of a nitroxide radical. Both peptides have eight solvent-shielded NH groups, suggesting that $3_{10}$-helical conformations are maintained in the two solvents. In alternating Aib-X sequences, the Aib residues appear to play a dominant role in determining the preferred conformations, overriding the intrinsic stereochemical preferences of the X residues.

Item Type: Journal Article http://www3.interscience.wiley.com/cgi-b... Copyright for this article belongs to John Wiley & Sons, Inc. Division of Biological Sciences > Molecular Biophysics Unit 15 Mar 2005 19 Sep 2010 04:18 http://eprints.iisc.ernet.in/id/eprint/2900