Crystal structure of NAD(P)H:flavin oxidoreductase from Escherichia coli
Crystal structure of NAD(P)H:flavin oxidoreductase from Escherichia coli
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DOI：
10.1021/bi982849m
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发表时间：
1999-06-01
期刊：
影响因子：
2.9
通讯作者：
Eklund, H
中科院分区：
文献类型：
--
作者：
Ingelman, M;Ramaswamy, S;Eklund, H
黄素还原酶以黄素为底物，与黄素紧密结合的黄素酶不同，还原后的黄素可以还原铁络合物和铁蛋白。在大肠杆菌中，核糖核苷酸还原酶的再激活是通过黄素还原酶产生的还原黄素来实现的。大肠杆菌黄素还原酶的晶体结构表明，该酶的结构与黄蛋白铁氧还蛋白还原酶家族的结构相似，尽管序列相似性非常低。黄素还原酶与结构相关的黄素蛋白的主要区别在于FAD的AMP部分没有结合位点。黄素结合域的螺旋方向也略有不同，与黄素蛋白中的磷酸结合螺旋相对应，不太适合磷酸结合。黄素底物的相互作用由疏水异氧嘧啶结合位点提供，该位点也含有丝氨酸和苏氨酸，在底物复合体中与结合核黄素的异氧嘧啶形成氢键。
Flavin reductases use flavins as substrates and are distinct from flavoenzymes which have tightly bound flavins, The reduced flavin can serve to reduce ferric complexes and iron proteins. In Escherichia coli, reactivation of ribonucleotide reductase is achieved by reduced flavins produced by flavin reductase, The crystal structure of E. coli flavin reductase reveals that the enzyme structure is similar to the structures of the ferredoxin reductase family of flavoproteins despite very low sequence similarities. The main difference between flavin reductase and structurally related flavoproteins is that there is no binding site for the AMP moiety of FAD. The direction of the helix in the flavin binding domain, corresponding to the phosphate binding helix in the flavoproteins, is also slightly different and less suitable for phosphate binding. Interactions for flavin substrates are instead provided by a hydrophobic isoalloxazine binding site that also contains a serine and a threonine, which form hydrogen bonds to the isoalloxazine of bound riboflavin in a substrate complex.