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Synthetic and conformational studies on dehydroalanine-containing model peptides

Gupta, Alka and Chauhan, VS (1990) Synthetic and conformational studies on dehydroalanine-containing model peptides. In: Biopolymers, 30 (3-4). pp. 395-403.

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Three model dipeptides containing a dehydroalanine residue (Ala) at the C-terminal, Boc-X-Ala-NHCH3 [X = Ala, Val, and Phe,] have been synthesized and their solution conformations investigated by 1H-NMR, IR, and CD spectroscopy. NMR studies on these peptides in CDCl3 clearly indicate that the NH group of dehydroalanine is involved in an intramolecular hydrogen bond. This conclusion is supported by IR studies also. Nuclear Overhauser effect (NOE) studies are also accommodative of an inverse -turn-type of conformation that is characterised by conformational angles of -70° and +70° around the X residue, and a C[stack i+1 ]H-Ni+2H interproton distance of 2.5 Å. It appears that unlike dehydrophenylalanine or dehydroleucine, which tend to stabilize -turn type of structures occupying the i + 2 position of the turn, dehydroalanine favors the formation of an inverse -turn, centered at the proceeding L-residue in such solvents as CDCl3 and (CD3)2SO. A comparison of solution conformation of Boc Val-Ala-NHCH3 with the corresponding saturated analogue, Boc-Val-Ala-NHCH3, is also presented and shows that dehydroalanine is responsible for inducing the turn structure. It may be possible to design peptides with different preferred conformations using the suitable dehydroamino acid.

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: 03 Jun 2010 10:12
Last Modified: 19 Sep 2010 06:00
URI: http://eprints.iisc.ac.in/id/eprint/27232

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