Hybrid αγ Polypeptides: Structural Characterization of a C12/C10 Helix with Alternating Hydrogen-Bond Polarity


  • We thank Dr. K. Nagarajan, Hikal R&D Centre, Bangalore, for gifts of 1-(aminomethyl)cyclohexaneacetic acid (Gpn) and for his continued interest. P.G.V. and S.C. thank the Council of Scientific and Industrial Research (CSIR), India, for the award of Senior Research Fellowships. Research grant support was from the CSIR, India, and from the Department of Biotechnology, India. The CCD facility is funded under the IRHPA program of the Department of Science and Technology, India.


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A different twist: A mixed C12/C10 helix with alternating hydrogen-bond directionality has been observed in the crystal structure of the hybrid αγ peptide Boc-Leu-Gpn-Leu-Aib-OMe (see structure; Boc: tert-butoxycarbonyl; Leu: leucine; Gpn: 1-(aminomethyl)cyclohexaneacetic acid (gabapentin); Aib: aminoisobutyric acid). The structure may be generalized to a regular mixed helix.