Crystallographically observed folded topology of an unsubstituted γ-aminobutyric acid incorporated in a model peptide: importance of a C--H···O interaction.
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)···H--N(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.
Kumar
Nigam
N
Institute of Microbial Technology (CSIR), Protein Science & Engineering Division, Sector 39-A, Chandigarh - 160 036, India.
Venugopalan
Paloth
P
Kishore
Raghuvansh
R
D018360:Crystallography, X-Ray; D004151:Dipeptides / Q000138:chemical synthesis / Q000737:chemistry*; D006860:Hydrogen Bonding; D008958:Models, Molecular; D015394:Molecular Structure; D017510:Protein Folding; D017550:Spectroscopy, Fourier Transform Infrared; D005680:gamma-Aminobutyric Acid / Q000737:chemistry*
D004151:Dipeptides; D005680:gamma-Aminobutyric Acid