Chandrappa, Siddappa and Aravinda, Subrayashastry and Raghothama, Srinivasarao and Sonti, Rajesh and Rai, Rajkishor and Harini, Veldore V and Shamala, Narayanaswamy and Balaram, Padmanabhan (2012) Helix and hairpin nucleation in short peptides using centrally positioned conformationally constrained dipeptide segments. In: Organic and Biomolecular Chemistry, 10 (14). pp. 2815-2823.
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The effect of incorporation of a centrally positioned Ac(6)c-Xxx segment where Xxx = (L)Val/(D)Val into a host oligopeptide composed of L-amino acid residues has been investigated. Studies of four designed octapeptides Boc-Leu-Phe-Val-Ac(6)c-Xxx-Leu-Phe-Val-OMe (Xxx = (D)Val 1, (L)Val 2) Boc-Leu-Val-Val-Ac(6)c-Xxx-Leu-Val-Val-OMe (Xxx = (D)Val 3, (L)Val 4) are reported. Diagnostic nuclear Overhouse effects characteristic of hairpin conformations are observed for Xxx = (D)Val peptides (1 and 3) while continuous helical conformation characterized by sequential NiH <-> Ni+1H NOEs are favored for Xxx = (L)Val 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 = (L)Val) 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 beta-turns may be used to nucleate helices in short peptides, while type I' beta-turns can facilitate folding into beta-hairpins.
|Item Type:||Journal Article|
|Additional Information:||Copyright of this article belongs to Royal Society of Chemistry.|
|Department/Centre:||Division of Biological Sciences > Molecular Biophysics Unit
Division of Physical & Mathematical Sciences > Physics
|Date Deposited:||20 Apr 2012 12:40|
|Last Modified:||20 Apr 2012 12:40|
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