Structure of tetragonal crystals of human erythrocyte catalase.
Structure of tetragonal crystals of human erythrocyte catalase.
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DOI：
10.1107/s0907444900013767
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发表时间：
2000-06
期刊：
影响因子：
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通讯作者：
M. Safo;F. Musayev;S. H. Wu;D. Abraham;T. Ko
中科院分区：
文献类型：
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作者：
M. Safo;F. Musayev;S. H. Wu;D. Abraham;T. Ko
以正交晶系晶体结构为搜索模型，用分子置换法确定了人红细胞过氧化氢酶（HEC）在空间群为I4（1）的四面体晶体中的结构。然后在尺寸为a = B = 203.6和c = 144.6 A的晶胞中对其进行细化，对于2.4 A分辨率的所有数据，分别产生0.196和0.244的R和R（自由）。与正交结构相比，四方晶体中的HEC结构的主要差异是省略了对应于人过氧化氢酶基因的第一外显子的20个残基的N-末端区段。两种晶型的整体结构在其他方面相同。NADPH结合位点是空的，在所有四个亚基和结合水分子观察到的活性位点。C-末端片段（对应于最后一个外显子）的结构仍未确定。四氢呋喃晶体的分子堆积呈准4（1）22对称性。两个类似类型的HEC四聚体之间的晶格接触界面进行了观察，它们相关的伪二轴。
The structure of catalase from human erythrocytes (HEC) was determined in tetragonal crystals of space group I4(1) by molecular-replacement methods, using the orthorhombic crystal structure as a search model. It was then refined in a unit cell of dimensions a = b = 203.6 and c = 144.6 A, yielding R and R(free) of 0.196 and 0.244, respectively, for all data at 2.4 A resolution. A major difference of the HEC structure in the tetragonal crystal compared with the orthorhombic structure was the omission of a 20-residue N-terminal segment corresponding to the first exon of the human catalase gene. The overall structures were otherwise identical in both crystal forms. The NADPH-binding sites were empty in all four subunits and bound water molecules were observed at the active sites. The structure of the C-terminal segment, which corresponds to the last exon, remained undetermined. The tetragonal crystals showed a pseudo-4(1)22 symmetry in molecular packing. Two similar types of lattice contact interfaces between the HEC tetramers were observed; they were related by the pseudo-dyad axes.