THE 2.3 ANGSTROM X-RAY STRUCTURE OF NITRITE REDUCTASE FROM ACHROMOBACTER-CYCLOCLASTES
THE 2.3 ANGSTROM X-RAY STRUCTURE OF NITRITE REDUCTASE FROM ACHROMOBACTER-CYCLOCLASTES
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DOI：
10.1126/science.1862344
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发表时间：
1991-07-26
期刊：
影响因子：
56.9
通讯作者：
LEGALL, J
中科院分区：
文献类型：
--
作者：
GODDEN, JW;TURLEY, S;LEGALL, J
通过同晶置换法，已确定来自环裂无色杆菌的含铜亚硝酸还原酶（NIR）的三维晶体结构，分辨率为2.3埃。该单体具有两个类似于质体蓝素的希腊钥匙β -桶状结构域，并含有两个铜位点。该酶在晶体中和溶液中均为三聚体。单体中的两个铜原子包含一个Ⅰ型铜位点（Cu - Ⅰ；两个组氨酸、一个半胱氨酸和一个甲硫氨酸配体）和一个假定的Ⅱ型铜位点（Cu - Ⅱ；三个组氨酸和一个溶剂配体）。尽管Cu - Ⅰ和Cu - Ⅱ由相邻的氨基酸配位，但它们相距约12.5埃。Cu - Ⅱ由并非来自单个单体，而是来自三聚体中两个单体的残基以近乎完美的四面体几何结构结合。Cu - Ⅱ位点位于一个12埃深的溶剂通道底部，是底物（NO₂⁻）结合的位点，这通过底物浸泡晶体和天然晶体的差值密度图得以证明。
The three-dimensional crystal structure of the copper-containing nitrite reductase (NIR) from Achromobacter cycloclastes has been determined to 2.3 angstrom (angstrom) resolution by isomorphous replacement. The monomer has two Greek key beta-barrel domains similar to that of plastocyanin and contains two copper sites. The enzyme is a trimer both in the crystal and in solution. The two copper atoms in the monomer comprise one type I copper site (Cu-I; two His, one Cys, and one Met ligands) and one putative type II copper site (Cu-II; three His and one solvent ligands). Although ligated by adjacent amino acids Cu-I and Cu-II are approximately 12.5 angstrom apart. Cu-II is bound with nearly perfect tetrahedral geometry by residues not within a single monomer, but from each of two monomers of the trimer. The Cu-II site is at the bottom of a 12 angstrom deep solvent channel and is the site to which the substrate (NO2-) binds, as evidenced by difference density maps of substrate-soaked and native crystals.