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首页> 外文期刊>Acta crystallographica.Section D. Biological crystallography >High-resolution refinement of orthorhombic bovine pancreatic phospholipase A2.
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High-resolution refinement of orthorhombic bovine pancreatic phospholipase A2.

机译：斜方晶系的牛的高分辨率细分胰腺磷脂酶A2。

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摘要

The X-ray structure of recombinant bovine pancreatic phospholipase A2 (PLA2), which specifically catalyzes the cleavage of the sn-2 acylester bond of phospholipids, has been refined at 1.5 A resolution. The crystal belongs to the space group P212121 with unit-cell parameters a = 47.12, b = 64.59 and c = 38.14 A similar to the native enzyme reported previously by Dijkstra et al. [J. Mol. Biol. (1981), 147, 97-123]. The refinement converged to an R value of 18.4% (Rfree = 22.8%) for 16 374 reflections between 10.0 and 1.5 A resolution. The surface-loop residues (60-70) are ordered in the present orthorhombic recombinant enzyme, but disordered in the trigonal recombinant enzyme. The active-site residues, His48, Asp99, and the catalytic water superimpose well with the trigonal form. Besides the catalytic water which is hydrogen bonded to His48, it is often seen that there is a second water attached to the same N atom of His48 and simultaneously hydrogen bonded to the O atom of Asp49. It is thought that the second water facilitates the tautomerism of His48 for enzyme catalysis. The catalytic water is also hydrogen bonded to the equatorial water coordinated to the calcium ion. In addition to the equatorial water, there is also an axial calcium water and the additional structural water. These five common water molecules are hydrogen bonded to the additional 16 water molecules in the present orthorhombic structure which may further enhance the structural integrity of the active site. Besides the protein and one calcium ion, a total of 134 water molecules were located in the present high-resolution refinement.
机译：重组牛的x射线结构胰腺磷脂酶A2 (PLA2)特别是催化sn-2的乳沟acylester债券的磷脂,雅致1.5一项决议。空间群P212121晶胞参数=47.12, b = 64.59和c = 38.14相似原生酶报告之前Dijkstra算法等艾尔。[J。改进聚合的R值18.4%(Rfree = 22.8%) 16 374之间的反射10.0和1.5的决议。残留物(60 - 70)命令在当下斜方晶系的重组酶,但无序在三方晶系的重组酶。活性位点残基、His48 Asp99,催化水重叠的三方晶系的形式。氢连着His48,经常看到吗还有一个水附加到相同的N原子His48同时氢连着Asp49 O原子。第二个水促进了互变现象His48酶催化。也是氢连着赤道水吗协调的钙离子。赤道的水,还有一个轴钙水和额外的结构水。氢连着额外的16个水分子在当下斜方晶系的结构这可能进一步加强结构活动网站的完整性。和一个钙离子,共有134名分子是坐落在当下高分辨率细分。

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