Hybrid peptide hairpins containing alpha- and omega-amino acids: Conformational analysis of decapeptides with unsubstituted beta-, gamma-, and delta-residues at positions 3 and 8

Rituparna, S Roy and Hosahudya, N Gopi and Raghothama, Srinivasarao and Karle, Isabella L and Balaram, Padmanabhan (2006) Hybrid peptide hairpins containing alpha- and omega-amino acids: Conformational analysis of decapeptides with unsubstituted beta-, gamma-, and delta-residues at positions 3 and 8. In: Chemistry - A European Journal, 12 (12). pp. 3295-3302.

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Abstract

The effects of inserting unsubstituted omega-amino acids into the strand segments of model beta-hairpin peptides was investigated by using four synthetic decapeptides, Boc-Lcu-Val-Xxx-Val-D-Pro-Gly-Leu-Xxx-Val-Val- OMe: pepticle 1 (Xxx=Gly), pepticle 2 (Xxx=beta Gly=beta hGly=homoglycine, beta-glycine), pepticle 3 (Xxx=gamma Abu=gamma-aminobutyric acid), pepticle 4 (Xxx= delta Ava=delta-aminovaleric acid). H-1 NMR studies (500 MHz, methanol) reveal several critical cross-strand NOEs, providing evidence for P-hairpin conformations in peptides 2-4. In peptide 3, the NMR results support the formation of the nucleating turn, however, evidence for cross-strand registry is not detected. Single-crystal X-ray diffraction studies of peptide 3 reveal a beta-hairpin conformation for both molecules in the crystallographic asymmetric unit, stabilized by four cross-strand hydrogen bonds, with the gamma Abu residues accommodated within the strands. The D-Pro-Gly segment in both molecules (A,B) adopts a type II' beta-turn conformation. The circular dichroism spectrum for peptide 3 is characterized by a negative CD band at 229 rim, whereas for peptides 2 and 4, the negative band is centered at 225 nm, suggesting a correlation between the orientation of the amide units in the strand segments and the observed CD pattern.

Item Type:	Journal Article
Publication:	Chemistry - A European Journal
Publisher:	John Wiley and Sons
Additional Information:	Copy right of this article belongs to John Wiley and Sons.
Keywords:	amino acids;conformation analysis;crystal structure; peptides;protein folding
Department/Centre:	Division of Biological Sciences > Molecular Biophysics Unit
Date Deposited:	29 Apr 2010 10:58
Last Modified:	19 Sep 2010 06:01
URI:	http://eprints.iisc.ac.in/id/eprint/27395

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