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首页> 外文期刊>Journal of chemical crystallography >Crystal structure and conformation of methionyl dipeptides: Structure of L-methionyl-L-asparagine: Preferred conformations of peptides containing methionyl and asparaginyl residues
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Crystal structure and conformation of methionyl dipeptides: Structure of L-methionyl-L-asparagine: Preferred conformations of peptides containing methionyl and asparaginyl residues

机译:甲硫酰基二肽的晶体结构和构象:L-甲硫酰基-L-天冬酰胺的结构:含有甲硫酰基和天冬酰胺基残基的肽的优选构象

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摘要

Crystals of L-methionyl-L-asparagines (C9N3H17O4S) are orthorhombic, space group P2(1)2(1)2(1), with cell parameters at 294 K of a = 5.248(1), b = 13.251(2), c = 18.028(2) angstrom, V = 1251.6(4) angstrom(3), Z = 4, D-m = 1.40 Mg/m(3), and D-x = 1.397 Mg/m(3). The crystal structure was solved by direct methods and refinded by full-matrix least-squares method to a final R value of 0.059 for 1804 reflections. The peptide is slightly nonpalnar [omega = 172.0(5)degrees]; the other torsion angles psi(1), phi(2), psi(2)(1), and psi(2)(2) are 155.6(5), -95.8(5), 152.5(5), and -29.4(6)degrees respectively. The methionyl side chain is disordered with two possible position for its C-gamma, S-delta, and C-epsilon atoms. The methionly side chain is twisted with chi(1) = -86.4(7), chi(2) = 177.5(9), and chi(3) = 116.6(2)degrees for the major conformer A. The asparaginyl side chain is also twisted with chi(1) = -76.3(5) and chi(2) = 102.3(6)degrees. The crystal structure is stabilized by an intermolecular network of hydrogen bonds involving the N-terminal amino group and the epsilon-terminal amino group of asn residue as donors and the carboxyl oxygens of the C-terminal and the peptide carbonyl oxygens as acceptor atoms.
机译:L-甲硫酰基-L-天冬酰胺(C9N3H17O4S)晶体是正交晶体,空间群P2(1)2(1)2(1),其单元参数在294 K时为a = 5.248(1),b = 13.251(2) c = 18.028(2)埃,V = 1251.6(4)埃,Z = 4,Dm = 1.40Mg / m(3),Dx = 1.397Mg / m(3)。通过直接方法解析晶体结构,并通过全矩阵最小二乘法将其晶体细化为1804次反射的最终R值为0.059。该肽为略非pal状[ω= 172.0(5)度];其他扭转角psi(1),phi(2),psi(2)(1)和psi(2)(2)为155.6(5),-95.8(5),152.5(5)和-29.4 (6)度。甲硫基侧链的C-γ,S-δ和C-ε原子有两个可能的位置无序。甲硫基侧链以主要构象异构体A的chi(1)= -86.4(7),chi(2)= 177.5(9)和chi(3)= 116.6(2)度扭转。天冬酰胺基侧链为也用chi(1)= -76.3(5)和chi(2)= 102.3(6)度扭曲。通过氢键的分子间网络来稳定晶体结构,该氢键的分子网络包括作为供体的asn残基的N-末端氨基和ε-末端氨基作为供体,以及C-末端的羧基氧和作为受体原子的肽羰基氧。

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