C9 Helices and Ribbons in γ-Peptides: Crystal Structures of Gabapentin Oligomers


  • This research was supported by a grant from the Council of Scientific and Industrial Research (CSIR) and Program Support in the area of Molecular Diversity and Design, Department of Biotechnology, India. We thank Dr. K. Nagarajan of Hikal R&D Centre, Bangalore (India), for the sample of gabapentin. P.G.V. and K.A. thank the CSIR for a senior research fellowship and research associateship, respectively. X-ray diffraction data were collected on the CCD facility funded under the IRHPA program of the Department of Science and Technology, India.


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Nine is the number: Novel C9-hydrogen-bonded structures (in which the hydrogen bonds enclose a ring of nine atoms) are observed in protected di- and tetrapeptides formed by the γ-amino acid residue gabapentin. The structures reveal new families of C9 helices and ribbons (see structure) in γ-polypeptides.