含脯氨酰残基的肽的结构与构象。IV. L-脯氨酰-L-亮氨酸一水合物。
Structure and conformation of peptides involving prolyl residue. IV. L-Prolyl-L-leucine monohydrate.
作者信息
Panneerselvam K, Chacko K K
机构信息
Department of Crystallography and Biophysics, University of Madras, India.
出版信息
Int J Pept Protein Res. 1990 May;35(5):460-4. doi: 10.1111/j.1399-3011.1990.tb00073.x.
The dipeptide, L-prolyl-L-leucine monohydrate (C11H20N2O3.H2O, molecular weight, 246.3) crystallizes in the monoclinic space group P2(1), with cell constants: a = 6.492(2)A, b = 5.417(8)A, c = 20.491(5)A, beta = 96.59(2) degrees, Z = 2, Do = 1.15 g/cm3, and Dc = 1.142 g/cm3. The structure was solved by SHELX-86 and refined by full matrix least squares methods to a final R-factor of 0.081 for 660 unique reflections (I greater than 2 sigma (I)) measured on an Enraf Nonius CAD-4 diffractometer (CuK alpha, lambda = 1.5418 A, T = 293 K). The peptide linkage exists in the trans conformation. The pyrrolidine ring exists in the envelope conformation. The values of the sidechain torsion angles are: chi 1 = -59.3(13) degrees, chi 21 = -63.1(16) degrees and chi 22 = 174.8(15) degrees for leucine (C-terminal). The crystal structure is stabilised by a three-dimensional network of N-H ... O, O-H ... O, and C-H ... O hydrogen bonds.
二肽L-脯氨酰-L-亮氨酸一水合物（C11H20N2O3·H2O，分子量246.3）以单斜空间群P2(1)结晶，晶胞参数为：a = 6.492(2)埃，b = 5.417(8)埃，c = 20.491(5)埃，β = 96.59(2)度，Z = 2，Do = 1.15克/立方厘米，Dc = 1.142克/立方厘米。该结构用SHELX - 86程序解析，并用全矩阵最小二乘法精修，对于在恩拉夫·诺尼乌斯CAD - 4衍射仪（CuKα，λ = 1.5418埃，T = 293K）上测量的660个独立反射（I大于2σ(I)），最终R因子为0.081。肽键以反式构象存在。吡咯烷环以信封式构象存在。亮氨酸（C端）的侧链扭转角值为：χ1 = -59.3(13)度，χ21 = -63.1(16)度，χ22 = 174.8(15)度。晶体结构通过N - H...O、O - H...O和C - H...O氢键的三维网络得以稳定。
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