creators_name: Thakur, A K
creators_name: Kishore, Raghuvansh
type: article
datestamp: 2012-01-04 14:55:57
lastmod: 2015-01-08 09:48:55
metadata_visibility: show
title: Influence of hydrophobic interactions on the conformational adaptability of the beta-Ala residue.
ispublished: pub
subjects: QD
full_text_status: restricted
keywords: b-Ala peptides; conformational analysis;
hydrophobic interactions; intermolecular interaction; X-ray
diffraction analysis.
note: Copyright of this article belongs to Wiley.
abstract: The chemical synthesis and X-ray crystal structure analysis of a model peptide incorporating a conformationally flexible beta-Ala residue: Boc-beta-Ala-Pda, 1 (C23H46N2O3: molecular weight = 398.62) have been described. The peptide crystallized in the crystal system triclinic with space group P21: a = 5.116(3) A, b = 5.6770(10) A, c = 21.744(5) A; alpha = 87.45 degrees, beta = 86.87 degrees, gamma = 90.0 degrees; Z = 1. An attractive feature of the crystal molecular structure of 1 is the induction of a reasonably extended backbone conformation of the beta-Ala moiety, i.e. the torsion angles phi approximately -115 degrees, mu approximately 173 degrees and psi approximately 122 degrees, correspond to skew-, trans and skew+ conformation, respectively, by an unbranched hydrophobic alkyl chain, Pda, which prefers an all-anti orientation (theta1 approximately -153 degrees, theta2 approximately ellipsis theta14 approximately +/-178 degrees ). The observation is remarkable because, systematic conformational investigations of short linear beta-Ala peptides of the type Boc-beta-Ala-Xaa-OCH3 (Xaa = Aib or Acc6) have shown that the chemical and stereochemical characters of the neighboring moieties may be critical in dictating the overall folded and/or unfolded conformational features of the beta-Ala residue. The overall conformation of 1 is typical of a 'bar'. It appears convincing that, in addition to a number of hydrophobic contacts between the parallel arranged molecules, an array of conventional N-HellipsisO=C intermolecular H-bonding interactions stabilize the crystal molecular structure. Moreover, the resulting 14-membered pseudo-ring motif, generated by the amide-amide interactions between the adjacent molecules, is completely devoid of nonconventional C-HellipsisO interaction. The potentials of the conformational adaptation of the beta-Ala residue, to influence and stabilize different structural characteristics have been highlighted.
date: 2001-06
date_type: published
publication: The journal of peptide research : official journal of the American Peptide Society
volume: 57
number: 6
publisher: Wiley
pagerange: 455-61
refereed: TRUE
issn: 1397-002X
official_url: http://onlinelibrary.wiley.com/doi/10.1034/j.1399-3011.2001.00839.x/abstract
related_url_url: http://onlinelibrary.wiley.com/doi/10.1034/j.1399-3011.2001.00839.x/abstract
related_url_type: pub
citation:   Thakur, A K and Kishore, Raghuvansh  (2001) Influence of hydrophobic interactions on the conformational adaptability of the beta-Ala residue.  The journal of peptide research : official journal of the American Peptide Society, 57 (6).  pp. 455-61.  ISSN 1397-002X     
document_url: http://crdd.osdd.net/open/294/1/kishore2001.pdf