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Crystallographically observed folded topology of an unsubstituted γ-aminobutyric acid incorporated in a model peptide: Importance of a C[BOND]H···O interaction

Authors

  • Nigam Kumar,

    1. Institute of Microbial Technology (CSIR), Protein Science & Engineering Division, Sector 39-A, Chandigarh - 160 036, India
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  • Paloth Venugopalan,

    1. Department of Chemistry, Panjab University, Sector 14, Chandigarh - 160 014, India
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  • Raghuvansh Kishore

    Corresponding author
    1. Institute of Microbial Technology (CSIR), Protein Science & Engineering Division, Sector 39-A, Chandigarh - 160 036, India
    • Institute of Microbial Technology (CSIR), Protein Science & Engineering Division, Sector 39-A, Chandigarh - 160 036, India
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  • Dedicated to Prof. P. Balaram in honor of his 60th birthday.

  • This article was originally published online as an accepted preprint. The “Published Online” date corresponds to the preprint version. You can request a copy of the preprint by emailing the Biopolymers editorial office at biopolymers@wiley.com

Abstract

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 Ni···H[BOND]Ni + 1 and an unconventional Ci[BOND]H···Oi 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.

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