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Issue 14, 2012
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Helix and hairpin nucleation in short peptides using centrally positioned conformationally constrained dipeptide segments

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Abstract

The effect of incorporation of a centrally positioned Ac6c-Xxx segment where Xxx = LVal/DVal into a host oligopeptide composed of L-amino acid residues has been investigated. Studies of four designed octapeptides Boc-Leu-Phe-Val-Ac6c-Xxx-Leu-Phe-Val-OMe (Xxx = DVal 1, LVal 2) Boc-Leu-Val-Val-Ac6c-Xxx-Leu-Val-Val-OMe (Xxx = DVal 3, LVal 4) are reported. Diagnostic nuclear Overhouse effects characteristic of hairpin conformations are observed for Xxx = DVal peptides (1 and 3) while continuous helical conformation characterized by sequential NiH ↔ Ni+1H NOEs are favored for Xxx = LVal peptides (2 and 4) in methanol solutions. Temperature co-efficient of NH chemical shifts are in agreement with distinctly different conformational preferences upon changing the configuration of the residue at position 5. Crystal structures of peptides 2 and 4 (Xxx = LVal) establish helical conformations in the solid state, in agreement with the structures deduced from NMR data. The results support the design principle that centrally positioned type I β-turns may be used to nucleate helices in short peptides, while type I′ β-turns can facilitate folding into β-hairpins.

Graphical abstract: Helix and hairpin nucleation in short peptides using centrally positioned conformationally constrained dipeptide segments

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Publication details

The article was received on 29 Oct 2011, accepted on 25 Jan 2012 and first published on 26 Jan 2012


Article type: Paper
DOI: 10.1039/C2OB06817F
Citation: Org. Biomol. Chem., 2012,10, 2815-2823
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    Helix and hairpin nucleation in short peptides using centrally positioned conformationally constrained dipeptide segments

    S. Chandrappa, S. Aravinda, S. Raghothama, R. Sonti, R. Rai, V. V. Harini, N. Shamala and P. Balaram, Org. Biomol. Chem., 2012, 10, 2815
    DOI: 10.1039/C2OB06817F

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