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Conformation of polypeptide-chains containing both l-residues and D-residues .2. Double-helical structures of poly-ld-peptides

Prasad, BV Venkatram and Chandrasekaran, R (1977) Conformation of polypeptide-chains containing both l-residues and D-residues .2. Double-helical structures of poly-ld-peptides. In: International Journal of Peptide and Protein Research, 10 (2). 129 -138.

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Official URL: http://www3.interscience.wiley.com/journal/1215309...


Polypeptides with alternating L- and D-amino acid residues can take up stereochemically satisfactory coaxial double-helical structures, both antiparallel and parallel, which are stabilized by systematic interchain NH O hydrogen bonds. Semiempirical energy calculations over allowed regions of conformational space have yielded the characteristics of these double-helices. There are four possible types of antiparallel double-helices - A3, A4, A5 and A6, with n, the number of LD peptide units per turn, around 2.8, 3.6, 4.5 and 5.5 respectively, while for the parallel double-helices there are two types, P3 and P4, having similar helical parameters as in A3 and A4. The hydrogen-bonding scheme restricts the pitch in all the models to the narrow range of 10.0 to 11.5 Å. All these helices have large central cores whose radii increase proportionately with n. In this respect, A3 and A4 are suitable models for the structure of gramicidin A. In terms of their relative energies, antiparallel double-helices are marginally more stable than those with parallel strands. Our results indicate that the energy differences amongst the members in the antiparallel family are not significant and thus provide an explanation for the polymorphism reported for poly(γ-benzyl-LD-glutamate).

Item Type: Journal Article
Publication: International Journal of Peptide and Protein Research
Publisher: Wiley
Additional Information: Copyright of this article belongs to Wiley.
Department/Centre: Division of Biological Sciences > Molecular Biophysics Unit
Date Deposited: 21 Jan 2010 06:27
Last Modified: 21 Jan 2010 06:27
URI: http://eprints.iisc.ac.in/id/eprint/24408

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