Directing peptide conformation with centrally positioned pre-organized dipeptide segments: studies of a 12-residue helix and beta-hairpin

Chandrappa, Siddappa and Reddy, MB Madhusudana and Sonti, Rajesh and Basuroy, Krishnayan and Raghothama, Srinivasarao and Balaram, Padmanabhan (2015) Directing peptide conformation with centrally positioned pre-organized dipeptide segments: studies of a 12-residue helix and beta-hairpin. In: AMINO ACIDS, 47 (2). pp. 291-301.

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Abstract

Secondary structure formation in oligopeptides can be induced by short nucleating segments with a high propensity to form hydrogen bonded turn conformations. Type I/III turns facilitate helical folding while type II'/I' turns favour hairpin formation. This principle is experimentally verified by studies of two designed dodecapeptides, Boc-Val-Phe-Leu-Phe-Val-Aib-Aib-Val-Phe-Leu-Phe-Val-OMe 1 and Boc-Val-Phe-Leu-Phe-Val- (D) Pro- (L) Pro-Val-Phe-Leu-Phe-Val-OMe 2. The N- and C-terminal flanking pentapeptide sequences in both cases are identical. Peptide 1 adopts a largely alpha-helical conformation in crystals, with a small 3(10) helical segment at the N-terminus. The overall helical fold is maintained in methanol solution as evidenced by NMR studies. Peptide 2 adopts an antiparallel beta-hairpin conformation stabilized by 6 interstrand hydrogen bonds. Key nuclear Overhauser effects (NOEs) provide evidence for the antiparallel beta-hairpin structure. Aromatic proton chemical shifts provide a clear distinction between the conformation of peptides 1 (helical) and 2 (beta-hairpin). The proximity of facing aromatic residues positioned at non-hydrogen bonding positions in the hairpin results in extensively ring current shifted proton resonances in peptide 2.

Item Type:	Journal Article
Publication:	AMINO ACIDS
Publisher:	SPRINGER WIEN
Additional Information:	Copy right for this article belongs to the SPRINGER WIEN, SACHSENPLATZ 4-6, PO BOX 89, A-1201 WIEN, AUSTRIA
Keywords:	alpha-Helix; beta-Hairpin; Peptide conformation; Aromatic residues
Department/Centre:	Division of Biological Sciences > Molecular Biophysics Unit
Date Deposited:	04 Mar 2015 12:37
Last Modified:	04 Mar 2015 12:37
URI:	http://eprints.iisc.ac.in/id/eprint/50979

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