MOLECULAR-STRUCTURE OF LEUCINE AMINOPEPTIDASE AT 2.7-A RESOLUTION
MOLECULAR-STRUCTURE OF LEUCINE AMINOPEPTIDASE AT 2.7-A RESOLUTION
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DOI：
10.1073/pnas.87.17.6878
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发表时间：
1990-09-01
影响因子：
11.1
通讯作者：
LIPSCOMB, WN
中科院分区：
文献类型：
--
作者：
BURLEY, SK;DAVID, PR;LIPSCOMB, WN
牛透镜亮氨酸氨肽酶（EC 3.4.11.1）与bestatin（一种缓慢结合抑制剂）复合的三维结构已被解析为3.0-.通过相位组合和密度修正的多重同晶置换法进行解析。此外，同晶天然酶的结构已在2.7-Δ G下得到改进。分辨率，并且对于包括两个锌离子和包含不对称单元的所有487个氨基酸残基的模型，当前晶体学R因子为0.169。该酶作为六聚体具有生理活性，其具有32对称性，并且是三角形形状，三角形边长为115埃。最大厚度为90埃。单体在晶体学上是等价的，并且每个单体折叠成两个不相等的α/。β的由α-连接的域螺旋以给出类似逗号的形状，最大尺寸约为90 ×55倍55.ANG.3.二级结构组成为40% α-螺旋和19% β-搁浅。N-末端结构域（160个氨基酸）介导三聚体-三聚体相互作用，并且似乎不直接参与催化，并且结合两个锌离子，其为2.88埃。apart.所述金属离子对位于八链鞍形β-环的边缘附近。床单。一个锌离子与Asp-255、Asp-332和Glu-334的羧酸氧原子和Asp-332的羰基氧配位。另一个锌离子与Asp-225、Asp-273和Glu-334的羧酸根氧原子配位。活性位点还含有两个带正电荷的残基，Lys-250和Arg-336。六个活性位点本身位于六聚体的内部，在那里它们排列成半径为15埃的盘形空腔。厚度为10埃。通过沿沿着双重对称轴线延伸的溶剂通道提供进入该腔的通路。
The three-dimensional structure of bovine lens leucine aminopeptidase (EC 3.4.11.1) complexed with bestatin, a slow-binding inhibitor, has been solved to 3.0-.ANG. resolution by the multiple isomorphous replacement method with phase combination and density modification. In addition, the structure of the isomorphous native enzyme has been refined at 2.7-.ANG. resolution, and the current crystallographic R factor is 0.169 for a model that includes the two zinc ions and all 487 amino acid residues comprising the asymmetric unit. The enzyme is physiologically active as a hexamer, which has 32 symmetry and is triangular in shape with a triangle edge length of 115 .ANG. and maximal thickness of 90 .ANG.. The monomers are crystallographically equivalent and each is folded into two unequal .alpha./.beta. domains connected by an .alpha.-helix to give a comma-like shape with approximate maximal dimensions of 90 .times. 55 .times. 55 .ANG.3. The secondary structural composition is 40% .alpha.-helix and 19% .beta.-strand. The N-terminal domain (160 amino acids) mediates trimer-trimer interaction and does not appear to participate directly in catalysis and binds the two zinc ions, which are 2.88 .ANG. apart. The pair of metal ions is located near the edge of an eight-stranded, saddle-shaped .beta.-sheet. One zinc ion is coordinated by carboxylate oxygen atoms of Asp-255, Asp-332, and Glu-334 and the carbonyl oxygen of Asp-332. The other zinc ion is coordinated by the carboxylate oxygen atoms of Asp-225, Asp-273, and Glu-334. The active site also contains two positively charged residues, Lys-250 and Arg-336. The six active sites are themselves located in the interior of the hexamer, where they line a disk-shaped cavity of radius 15 .ANG. and thickness 10 .ANG.. Access to this cavity is provided by solvent channels that run along the twofold symmetry axes.