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首页> 外文期刊>Acta crystallographica.Section D. Biological crystallography >Structure of xylose isomerase from Streptomyces diastaticus No. 7 strain M1033 at 1.85 A resolution
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Structure of xylose isomerase from Streptomyces diastaticus No. 7 strain M1033 at 1.85 A resolution

机译：木糖异构酶的结构从链霉菌属diastaticus 7号菌株M1033 1.85决议

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摘要

The structure of xylose isomerase (XyI) from Streptomyces diastaticus No. 7 strain M1033 (SDXyI) has been refined at 1.85 A resolution to conventional and free R factors of 0.166 and 0.219, respectively. SDXyI was crystallized in space group P2_12_12, with unit-cell parameters a = 87.976, b = 98.836, c = 93.927 A. One dimer of the tetrametric molecule is found in each asymmetric unit. Each monomer consists of two domains: a large N-terminal domain (residues 1-320), containing a parallel eight-stranded α/β barrel, and a small C-terminal loop (residues 321-387), containing five helices linked by random coil. The four monomers are essentially identical in the tetramer, possessing non-crystallographic 222 symmetry with one twofold axis essentially coincident with the crystallographic twofold axis in the space group P2_12_12, which may explain why the diffraction pattern has strong pseudo-I222 symmetry even at medium resolution. The crystal structures of XyIs from different bacterial strains, especially from Streptomyces, are similar. The α2 helix of the α/β barrel has a different position in the structures of different XyIs. The conformation of C-terminal fragment 357-364 in the SDXyI structure has a small number of differences to that of other XyIs. Two Co~(2+) ions rather than Mg~(2+) ions exist in the active site of the SDXyI structure; SDXyI seems to prefer to bind Co~(2+) ions rather than Mg~(2+) ions.
机译：木糖异构酶的结构(XyI)链霉菌属diastaticus M1033 7号压力1.85 (SDXyI)一直在完善解决传统和自由R 0.166和要素0.219,分别。空间群P2_12_12,晶胞参数= 87.976, b = 98.836, c = 93.927。tetrametric分子被发现不对称单元。域:一个大n端结构域(残留物1 - 320),包含一个平行eight-strandedα/β桶,和一个小c端循环(残留物321 - 387),包含五个螺旋线联系在一起的随机线圈。拥有相同的四聚物non-crystallographic 222对称两个轴的基本重合晶体空间群的两个轴P2_12_12,这或许可以解释为什么衍射即使在模式有很强的pseudo-I222对称中等分辨率。从不同的菌株,尤其是来自链霉菌属,是相似的。α/β桶有不同的位置XyIs结构不同。c端片段SDXyI 357 - 364结构有小数量的差异其他XyIs。毫克~(2 +)离子活性位点的存在SDXyI结构;公司~(2 +)离子而不是毫克~(2 +)离子。

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