Bilin-metabolizing Enzymes: Site-specific Reductions Catalyzed by Two Different Type of Enzymes
Bilin-metabolizing Enzymes: Site-specific Reductions Catalyzed by Two Different Type of Enzymes
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胆碱代谢酶：两种不同类型酶催化的位点特异性还原
DOI：
10.1016/j.sbi.2019.03.005
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发表时间：
2019
影响因子：
6.8
通讯作者：
K.
中科院分区：
文献类型：
--
作者：
Sugishima;M.;Wada;K.;Unno;M.;Fukuyama;K.
亮点胆绿素(BV)被BVR或FDBRs还原，它们彼此不同。BV的两个分子堆积在BVR-A的结合位置。与BVR-A结合的两个BV中的一个不是底物，但参与了反应。PcyA的中子结构阐明了BV的质子化状态和某些残基。在哺乳动物中，绿色的血红素代谢物胆绿素被NAD(P)H依赖的胆绿素还原酶(BVR)转化为黄色抗氧化剂。而在依赖氧气的光合作用生物体中，它被铁还蛋白依赖的胆红素还原酶(FDBRs)转化为光合色素或光敏色素。在NADP+结合和胆绿素结合的BVR-A中，两个胆绿素堆积在结合裂隙处；一个定位为接受来自NADPH的氢化物，另一个似乎通过邻近的精氨酸残基向第一个胆绿素提供质子。在FDBR催化的反应中，电子和质子分别从铁氧还蛋白和FDBRs和结合在FDBRs中的水提供给胆红素。因此，比林和催化残基的质子化中心对于分析特定位置的还原是很重要的。FDBR的中子结构揭示了这个问题。
HighlightsBiliverdin (BV) is reduced by BVR or FDBRs, which do not resemble each other.Two molecules of BV are stacked in the binding site of BVR-A.One of the two BVs bound to BVR-A is not the substrate, but is involved in the reaction.The neutron structure of PcyA elucidates the protonation states of BV and certain residues.Unstable hydronium ion is present in the neutron structure of PcyA.In mammals, the green heme metabolite biliverdin is converted to a yellow anti-oxidant by NAD (P) H-dependent biliverdin reductase (BVR), whereas in O 2-dependent photosynthetic organisms it is converted to photosynthetic or light-sensing pigments by ferredoxin-dependent bilin reductases (FDBRs). In NADP+-bound and biliverdin-bound BVR-A, two biliverdins are stacked at the binding cleft; one is positioned to accept hydride from NADPH, and the other appears to donate a proton to the first biliverdin through a neighboring arginine residue. During the FDBR-catalyzed reaction, electrons and protons are supplied to bilins from ferredoxin and from FDBRs and waters bound within FDBRs, respectively. Thus, the protonation sites of bilin and catalytic residues are important for the analysis of site-specific reduction. The neutron structure of FDBR sheds light on this issue.