Peptide models for b-turns.A circular dichroism study

Crisma, M and Fasman, GD and Balaram, H and Balaram, Padmanabhan (1984) Peptide models for b-turns.A circular dichroism study. In: International Journal of Peptide and Protein Research, 23 (4). pp. 411-419.

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Abstract

The circular dichroism spectra of four 0-turn model peptides, Z-Aib-Pro-Aib-Pro- OMe (l), Piv-Pro-Aib-NHMe (2), Piv-Pro-D-Ala-NHMe (3) and Piv-Pro-Val-NHMe (4) have been examined under a wide range of solvent conditions, using methanol, hexafluoroisopropanol and cyclohexane. Type I and Type I1 0-turns have been observed for peptides 1 and 2 respectively, in the solid state, while the Pro-D-Ala sequence adopts a Type I1 Sturn in a related peptide crystal structure. A class C spectrum is observed for 1 in various solvents, suggesting a variant of a Type I(II1) structure. The Type I1 f3-turn is characterized by a CD spectrum having two positive CD bands at - 230 nm and - 202 nm, a feature observed in Piv-Pro- D-Ala-NHMe in cyclohexane and methanol and for Piv-Pro-Aib-NHMe in methanol. Peptide 2 exhibits solvent dependent CD spectra, which may be rationalized by considering Type 11, I11 and V reverse turn structures. Piv-Pro- Val-NHMe adopts nonaturn structures in polar solvents, but exhibits a class B spectrum in cyclohexane suggesting a population of Type I &turns.

Item Type:	Journal Article
Publication:	International Journal of Peptide and Protein Research
Publisher:	John Wiley & Sons
Additional Information:	Copyright of this article belongs to John Wiley & Sons.
Keywords:	a-aminoisobutyryl peptides; circular dichroism; peptide conformation; proline peptides; p-turns.
Department/Centre:	Division of Biological Sciences > Molecular Biophysics Unit
Date Deposited:	29 Oct 2010 06:06
Last Modified:	29 Oct 2010 06:06
URI:	http://eprints.iisc.ac.in/id/eprint/33475

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