Dinesh, Bhimareddy and Vinaya, Vishwanathan and Raghothama, Srinivasarao and Balaram, Padmanabhan (2013) C12-Helix development in ()n sequences - spectroscopic characterization of Boc-Aib-4(R)Val]-OMe oligomers. In: European Journal of Organic Chemistry (17). pp. 3590-3596.
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Abstract
The solution conformations of the -hybrid oligopeptides Boc-Aib-4(R)Val]n-OMe (n = 1-8) in organic solvents have been probed by NMR, IR, and CD spectroscopic methods. In the solid state, this peptide series favors C12-helical conformations, which are backbone-expanded analogues of 310 helices in -peptide sequences. NMR studies of the six- (n = 3) and 16-residue (n = 8) peptides reveal that only two NH protons attached the N-terminus residues Aib(1) and 4(R)Val(2) are solvent-exposed. Sequential NiH-Ni+1H NOEs characteristic of local helical conformations are also observed at the residues. IR studies establish that chain extension leads to a large enhancement in the intensities of the hydrogen-bonded NH stretching bands (3343-3280 cm-1), which suggest elongation of intramolecularly hydrogen-bonded structures. The development of C12-helical structures upon lengthening of the sequence is supported by the NMR and IR observations. The CD spectra of the ()n peptides reveal a negative maximum at ca. 206 nm and a positive maximum at ca. 192 nm, spectral feature that are distinct from those of 310 helices in -peptides.
Item Type: | Journal Article |
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Publication: | European Journal of Organic Chemistry |
Publisher: | John Wiley and Sons |
Additional Information: | Copyright of this article belongs to John Wiley and Sons. |
Keywords: | Peptides; Amino Acids; Helical Structures; Conformation Analysis |
Department/Centre: | Division of Biological Sciences > Molecular Biophysics Unit Division of Chemical Sciences > NMR Research Centre (Formerly Sophisticated Instruments Facility) |
Date Deposited: | 19 Jul 2013 07:17 |
Last Modified: | 19 Jul 2013 07:17 |
URI: | http://eprints.iisc.ac.in/id/eprint/46854 |
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