A helical peptide (hexamer)

Both diastereomeric right-handed (P) and left-handed (M) 310-helices exist in homopeptides having twelve chiral centers at the side-chain bicyclic skeletons. Masakazu Tanaka, Kosuke Anan, Yosuke Demizu, Masaaki Kurihara, Mitsunobu Doi, and Hiroshi Suemune Side-chain chiral centers of amino acid and helical-screw handedness of its peptides. J. Am. Chem. Soc., 33, 3333-3333 (2005).

310-helices Skyblue ribbons: left-handed Yellow ribbons: right-handed drawn by iMol @Aug. 2005

X-Ray Data Summary formula 4[C67H92N6O9, 0.5(C2H6O)] weight 4594.0 symmetry triclinic space group P1 Cell Crystal a 15.765(12) Ang. description block b 16.535(10) Ang. colour colourless c 26.90(2) Ang. size 0.6×0.5×0.4 mm^3 α 74.22(3) deg. Dx 1.171 g/ml β 82.32(3) deg. F(000) 2484 γ 75.39(3) deg. μ 0.078 mm^-1 volume 6514(8) Ang^3 Radiation Mo Kα Z 4 Diffrn measurement Refinement device type Rigaku RAXIS RAPID Flack 1.3(9) Rint 0.0530 parameters 3045 T 150 K restraints 477 θmax (deg.) 27.49 R1 0.0589 total reflections 29059 wR 0.1349 reflections(obs) 14531 .gt. 2σ(I) Δρmax 0.513 e A^-3 Structure Δρmin -1.180 e A^-3 solution SHELXD Δ/σmax 0.005 refinement SHELXL-97 Goodness of fit 0.885 Get PDB coordinates

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