Subramanian E, Sahayamary J J
Department of Crystallography and Biophysics, University of Madras, India.
Int J Pept Protein Res. 1989 Aug;34(2):134-8. doi: 10.1111/j.1399-3011.1989.tb01502.x.
The crystal structure of a tripeptide, tryptophanyl-glycyl-glycine dihydrate (C15H18N4O4.2H2O, molecular weight = 354) has been determined. The crystals are orthorhombic, space group P2(1)2(1)2(1), with a = 7.875 (1) A, b = 9.009(1), c = 24.307(1) and Z = 4. The final R-index is 0.058 for 1488 reflections [sin theta)/lambda less than or equal to 0.6 A-1) with I greater than 2 sigma (I). The molecule exists as a zwitterion, with terminal NH3+ and COO- groups. The peptide units are trans and nearly perpendicular to the plane of the carboxyl group. The backbone torsion angles are: psi 1 = 132.7 degrees, omega 1 = 174.2 degrees, phi 2 = 88.2 degrees, psi 2 = 8.6 degrees, omega 2 = -179.8 degrees, phi 3 = -85.2 degrees, psi 31 = -178.1 degrees, psi 32 = 5.0 degrees. For the sidechain of tryptophan, chi 1 = -171.6 degrees, chi 2 = 101.0 degrees.
已确定三肽色氨酰 - 甘氨酰 - 甘氨酸二水合物（C15H18N4O4·2H2O，分子量 = 354）的晶体结构。晶体为正交晶系，空间群P2(1)2(1)2(1)，a = 7.875 (1) Å，b = 9.009(1)，c = 24.307(1)，Z = 4。对于1488个[sinθ/λ≤0.6 Å-1且I>2σ(I)]反射，最终R指数为0.058。该分子以两性离子形式存在，带有末端NH3+和COO-基团。肽单元为反式且几乎垂直于羧基平面。主链扭转角为：ψ1 = 132.7°，ω1 = 174.2°，φ2 = 88.2°，ψ2 = 8.6°，ω2 = -179.8°，φ3 = -85.2°，ψ31 = -178.1°，ψ32 = 5.0°。对于色氨酸侧链，χ1 = -171.6°，χ2 = 101.0°。
