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Crystal structure of Boc-LAla-Delta Phe-Delta Phe-Delta Phe-Delta Phe-NHMe: a left-handed helical peptide

Ramagopal, UA and Ramakumar, S and Joshi, R and Chauhan, VS (1998) Crystal structure of Boc-LAla-Delta Phe-Delta Phe-Delta Phe-Delta Phe-NHMe: a left-handed helical peptide. In: Journal of Peptide Research, 52 (3). pp. 208-215.

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Official URL: http://onlinelibrary.wiley.com/doi/10.1111/j.1399-...


alpha,beta-Dehydrophenylalanine residues constrain the peptide backbone to beta-bend conformation. A pentapeptide containing four consecutive (Delta Phe) residues has been synthesised and crystallised. The peptide Boc-LAla-Delta Phe-Delta Phe-Delta Phe-Delta Phe-NHMe (C45H46N6O7, MW = 782.86) was crystallised from an acetonitrile/methanol mixture. The crystal belongs to the orthorhombic space group P2(1)2(1)2(1) With a = 19.455(6), b = 20.912(9), c = 11.455(4) Angstrom and Z = 4. The X-ray (MoKalpha, lambda = 0.7107 Angstrom) intensity data were collected using the Rigaku-AFC7 diffractrometer. The crystal structure was determined by direct methods and refined using the least-squares technique, R = 8.41% for 1827 reflections with \F-o\ > 4 sigma\F-o\. The molecule contains the largest stretch of consecutive dehydrophenylalanine residues whose crystal structure has been determined so far. The peptide adopts left-handed 3(10)-helical conformation despite the presence of LAla at the N-terminus. The mean phi, psi values, averaged across the last four residues are 56.8 degrees and 17.5 degrees, respectively. There are four 4-->1 intramolecular hydrogen bonds, characteristic of the 3(10)-helix. In the crystal each molecule interacts with four crystallographically symmetric molecules with one hydrogen bond each.

Item Type: Journal Article
Publication: Journal of Peptide Research
Publisher: John Wiley and Sons
Additional Information: Copyright of this article belongs to John Wiley and Sons.
Keywords: Molecular-Structure;Solid-State;Screw Sense;Pentapeptide; Residues;Ome;Dehydropeptide;Conformation;Nonapeptide.
Department/Centre: Division of Physical & Mathematical Sciences > Physics
Date Deposited: 09 Jun 2011 07:46
Last Modified: 09 Jun 2011 07:46
URI: http://eprints.iisc.ac.in/id/eprint/38083

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