A nonhelical, multiple β-turn conformation in a glycine-rich heptapeptide fragment of trichogin A IV containing a single central α-aminoisobutyric acid residue

Gurunath, R and Balaram, Padmanabhan (1995) A nonhelical, multiple β-turn conformation in a glycine-rich heptapeptide fragment of trichogin A IV containing a single central α-aminoisobutyric acid residue. In: Biopolymers, 35 (01). pp. 21-29.

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Abstract

The conformational properties of the protected seven-residue C-terminal fragment the lipopeptaibol antibiotic Trichogin A IV (Boc-Gly-Gly-Leu-Aib-Gly-Ile-Leu-OMe) has been examined in CDCl3 and (CD3)2SO by 1H-nmr. Evidence for a multiple β-turn conformation [type I′ at Gly(1)-Gly(2), type II at Leu(3)-Aib(4), and a type I′ at Aib(4)-Gly(5)] suggests that Leu(3) has preferred an extended or semiextended conformation over a helical conformation in CDCl3. This structure is thus in contrast to earlier observations of seven-residue peptides containing a single central Aib preferring helical conformations in both solution and crystalline slates. A structural transition to a frayed right-handed helix is absented in (CD3)2SO. These results suggest that nonhelical conformations may be important in Gly-rich peptides containing Aib. Further, the presence of amino acids with contradictory influences on backbone conformational freedom can lead to well-defined conformational transitions even in small peptides

Item Type:	Journal Article
Publication:	Biopolymers
Publisher:	John Wiley & Sons
Additional Information:	Copyright of this article belongs to John Wiley & Sons.
Department/Centre:	Division of Biological Sciences > Molecular Biophysics Unit
Date Deposited:	11 Nov 2010 05:29
Last Modified:	11 Nov 2010 05:29
URI:	http://eprints.iisc.ac.in/id/eprint/33744

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