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Crystallographically observed folded topology of an unsubstituted γ‐aminobutyric acid incorporated in a model peptide: Importance of a CH···O interaction
Author(s) -
Kumar Nigam,
Venugopalan Paloth,
Kishore Raghuvansh
Publication year - 2010
Publication title -
biopolymers
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.556
H-Index - 125
eISSN - 1097-0282
pISSN - 0006-3525
DOI - 10.1002/bip.21511
Subject(s) - chemistry , intramolecular force , intermolecular force , hydrogen bond , peptide , crystallography , amide , molecule , topology (electrical circuits) , infrared spectroscopy , non covalent interactions , stereochemistry , organic chemistry , biochemistry , mathematics , combinatorics
To validate the existing hypothesis put forward by Navarro et al., we performed single crystal X‐ray diffraction structural analysis of a designed model peptide incorporating an unsubstituted achiral γ‐aminobutyric acid: Boc‐Pro‐γ‐Abu‐OH ( 1 ) lacking C‐terminal amide group. The analysis established existence of an overall unusual tightly folded topology stabilized by a conventional N i ···HN i + 1 and an unconventional C i H···O i type intramolecular hydrogen bonding interactions, encompassing a five‐membered and a six‐membered ring motifs, respectively. Moreover, in conjunction with Fourier transform infrared (FT‐IR) absorption study in solid KBr, the results provided evidence that two conventional and one unconventional noncovalent intermolecular interaction stabilize a right‐handed helical architecture generated via molecular self‐assembly by translating the symmetry related molecules along the crystallographic b axis. © 2010 Wiley Periodicals, Inc. Biopolymers 93: 927–931, 2010.