Structural and redox plasticity in the heterodimeric periplasmic nitrate reductase
Structural and redox plasticity in the heterodimeric periplasmic nitrate reductase
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DOI：
10.1038/nsb994
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发表时间：
2003-11-01
期刊：
影响因子：
--
通讯作者：
Pignol, D
中科院分区：
文献类型：
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作者：
Arnoux, P;Sabaty, M;Pignol, D
呼吸硝酸还原酶（NapAB）的结构，从球形红细菌，周质异二聚体酶负责的第一步在反硝化过程中，已被确定在3.2埃的分辨率。二血红素电子转移小亚基NapB与大亚基结合，血红素II靠近NapA的[4Fe-4S]簇。在NapB的N-和C-末端末端共有57个残基采用延伸构象，包含NapA亚基，并在很大程度上贡献了复合物中5，900埃的总面积。通过测量结合后所有辅因子的氧化还原电位的变化来进一步研究复合物的形成。所观察到的显着效果的三维结构的光解释和描绘的可塑性，有助于一个有效的电子转移在复杂的从血红素我的NapB的钼催化位点的NapA。
The structure of the respiratory nitrate reductase (NapAB) from Rhodobacter sphaeroides, the periplasmic heterodimeric enzyme responsible for the first step in the denitrification process, has been determined at a resolution of 3.2 Angstrom. The di-heme electron transfer small subunit NapB binds to the large subunit with heme II in close proximity to the [4Fe-4S] cluster of NapA.. A total of 57 residues at the N- and C-terminal extremities of NapB adopt an extended conformation, embracing the NapA subunit and largely contributing to the total area of 5,900 Angstrom(2) buried in the complex. Complex formation was studied further by measuring the variation of the redox potentials of all the cofactors upon binding. The marked effects observed are interpreted in light of the three-dimensional structure and depict a plasticity that contributes to an efficient electron transfer in the complex from the heme I of NapB to the molybdenum catalytic site of NapA.