Left-handed 310- and α-helix homopeptides



Paper Angewandte Chemie International Edition  43(40), 5360-5363 (2004). Masakazu Tanaka, Yosuke Demizu, Mitsunobu Doi, Masaaki Kurihara, Hiroshi Suemune
VIP: Chiral centers in the side chains of α-amino acids control the helical screw sense of peptides.
ABSTRACT: The screw sense of 310- and &alpha-helices formed by the oligopeptides, which have no &alpha-carbon chiral centers, is controlled by the chiral centers in their side chains. These results imply that just the side chain chiral centers of isoleucine and threonine would affect the secondary structure of their oligopeptides.

    X-Ray Summary of Hexamer 
    Formula         3(C57H88N6O21)
    Mr              3580.0
    System          monoclinic
    Space group     P21
    a               22.889(3)
    b               11.906(1)
    c               33.711(4)
    β               91.887(2)
    V               9182(2)
    Z               6
    T, K            90.0(2)
    Dx              1.295
    F(0 0 0)        3840
    Wavelength      0.7107
    μ               0.099
    NREF (obs)      88263
    Rint            0.0326
    NREF (used)     31196
    θmax            24.7
    R               0.0775
    wR              0.1972

    PDB coord.      here


Top view of Molecule 1


Left-handed 310-helix of
(three molecules)


    X-Ray Summary of Octamer 
    Formula         C73H114N8O27
    Solvation       3(H2O)
    Mr              1589.8
    System          monoclinic
    Space group     P21
    a               15.639(13)
    b               6.431(10)
    c               15.989(11)
    β               95.85(3)
    V               4087(5)
    Z               2
    T, K            123(2)
    Dx              1.292
    F(0 0 0)        1708
    Wavelength      0.7107
    μ               0.100
    NREF (obs)      64220
    Rint            0.0609
    NREF (used)     31496
    θ max           27.47
    R               0.0579
    wR              0.1401

    PDB coord.      here




   =======================================
   *If you used these hexamer and octamer 
    coordinates for your research, please 
    refer to Angew. Chem. Int. Ed. 43(40), 
    5360-5363 (2004) in your manuscript.
   =======================================



Left-handed α-helix


Top view
These figures are drawn by iMol.
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