\alpha-\gamma Hybrid Peptides that Contain the Conformationally Constrained Gabapentin Residue: Characterization of Mimetics of Chain Reversals

Aravinda, Subrayashastry and Ananda, Kuppanna and Shamala, Narayanaswamy and Balaram, Padmanabhan (2003) \alpha-\gamma Hybrid Peptides that Contain the Conformationally Constrained Gabapentin Residue: Characterization of Mimetics of Chain Reversals. In: Chemistry - A European Journal, 9 (19). pp. 4789-4795.

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Abstract

The crystal structures of four dipeptides that contain the stereochemically constrained gamma-amino acid residue gabapentin (1-(aminomethyl) cyclohexaneacetic acid Gpn) are described. The molecular conformation of Piv-Pro-Gpn-OH (1), reveals a beta-turn mimetic conformation, stabilized by a ten atom C-H…O hydrogen bond between the Piv CO group and the pro S hydrogen of the Gpn CH2-CO group. The peptides Boc-Gly-Gpn-OH (2),Boc-Aib- Gpn-OH (3),and Boc-Aib-Gpn-OMe (4) form compact,folded structures,in which a distinct reversal of polypeptide chain direction is observed. In all cases, the Gpn residue adopts a gauche, gauche (g,g) conformation about the C alpha-C gamma (tita1) and C beta-C alpha (tita 2) bonds. Two distinct Gpn conformational families are observed. In peptides 1 and 3,the average backbone torsion angle values for the Gpn residue are 98, 1, 62, 2, 73 and 79,while in peptide 2 and 4 the average values are -103, -1, - 46, - 49 and - 92. In the case of 1 and 3,an intramolecular nine membered O-H…O hydrogen bond is formed between the C=O of the preceding residue and the terminal carboxylic acid OH group. All four alpha-gamma dipeptide sequences yield compact folded backbone conformations; this suggests that the Gpn residue may be employed successfully in the design of novel folded structures.

Item Type:	Journal Article
Publication:	Chemistry - A European Journal
Publisher:	John Wiley & Sons, Inc
Additional Information:	Copyright for this article belongs to John Wiley & Sons, Inc
Keywords:	Amino acids;beta-turn mimetics;Hydrogen bonds;Peptides;Structure elucidation
Department/Centre:	Division of Biological Sciences > Molecular Biophysics Unit Division of Physical & Mathematical Sciences > Physics
Date Deposited:	02 May 2006
Last Modified:	19 Sep 2010 04:14
URI:	http://eprints.iisc.ac.in/id/eprint/1217

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