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首页> 外文期刊>Acta crystallographica.Section D. Biological crystallography >Polymorphism of microcrystalline urate oxidase from Aspergillus flavus.
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Polymorphism of microcrystalline urate oxidase from Aspergillus flavus.

机译：微晶尿酸氧化酶的多态性从黄曲霉。

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摘要

Different polymorphs of rasburicase, a recombinant urate oxidase enzyme (Uox) from Aspergillus flavus, were obtained as a series of polycrystalline precipitates. Different crystallization protocols were followed in which the salt type, pH and polyethylene glycol 8000 (PEG 8000) concentration were varied. The related crystalline phases were characterized by means of high-resolution synchrotron X-ray powder diffraction. In all cases, Uox complexed with the inhibitor 8-azaxanthine (AZA) was not altered from its robust orthorhombic I222 phase by variation of any of the factors listed above. However, in the absence of AZA during crystallization ligand-free Uox was significantly affected by the type of salt, resulting in different crystal forms for the four salts tested: sodium chloride, potassium chloride, ammonium chloride and ammonium sulfate. Remarkable alterations of some of these phases were observed upon gradual increase of the exposure time of the sample to the synchrotron beam in addition to variation of the PEG 8000 concentration. When Uox was crystallized in Tris buffer or pure water in the absence of salt, a distinct polymorph of orthorhombic symmetry (P2(1)2(1)2) was obtained that was associated with significantly altered lattice dimensions in comparison to a previously reported isosymmetrical structure. The latter form of Uox exhibits enhanced stability to variation of pH and PEG 8000 concentration accompanied by minor modifications of the unit-cell dimensions in the ranges under study. Accurate lattice parameters were extracted for all crystalline phases. This study reveals the rich phase diagram of Uox, a protein of high pharmaceutical importance, which is associated with an enhanced degree of polymorphism. The outcome of our analysis verifies previously reported results as well as demonstrating polymorphs that have altered unit-cell dimensions with respect to known structural models.
机译：不同的多晶型物rasburicase,重组尿酸盐氧化酶酶(Uox)从曲霉菌flavus,得到一系列的多晶沉淀。随访中结晶协议盐类型、pH值和聚乙二醇8000(8000年挂钩)浓度变化。结晶阶段的特征高分辨率同步x射线粉末衍射。抑制剂8-azaxanthine(阿扎)并没有改变从其健壮的斜方晶系的I222阶段上面列出的任何因素的变化。然而,在没有阿扎结晶ligand-free Uox明显影响盐的类型,导致不同的晶体形式的四个盐测试:氯化钠、氯化钾氯化铵、硫酸铵。这些阶段的显著改变观察在逐渐增加的吗曝光时间同步的样本梁除了8000年变化的挂钩浓度。缓冲或纯水没有盐,a独特的斜方晶系的对称变形(P2(1) 2(1) 2)获得相关与显著改变晶格尺寸相比先前报道isosymmetrical结构。展品增强稳定pH值的变化和8000浓度伴随着小挂钩修改的单胞尺寸在研究范围。所有水晶提取阶段。Uox的研究揭示了丰富的相图蛋白质高制药的重要性,与一个增强的程度多态性。以及验证之前报道的结果多晶型物证明一些东西改变了单胞尺寸已知的结构模型。

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