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首页> 外文期刊>Dalton transactions: An international journal of inorganic chemistry >Quantum chemical studies of dioxygen activation by mononuclear non-heme iron enzymes with the 2-His-l-carboxylate facial triad
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Quantum chemical studies of dioxygen activation by mononuclear non-heme iron enzymes with the 2-His-l-carboxylate facial triad

机译：2-His-1-羧酸盐面部三联体通过单核非血红素铁酶激活双氧的量子化学研究

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摘要

Density functional theory with the B3LYP hybrid functional has been used to study the mechanisms for dioxygen activation by four families of mononuclear non-heme iron enzymes:a-ketoacid-dependent dioxygenases,tetrahydrobiopterin-dependent hydroxylases,extradiol dioxygenases,and Rieske dioxygenases.These enzymes have a common active site with a ferrous ion coordinated to two histidines and one carboxylate group(aspartate or glutamate).In contrast to the heme case,this type of weak field environment always leads to a high-spin ground state.With the exception of the Rieske dioxygenases,which have an electron source outside the active site,the dioxygen activation process passes through the formation of a bridging-peroxide species,which then undergoes O-O bond cleavage finally leading to the four electron reduction of O_2-In the case of tetrahydrobiopterin-and a-ketoacid-dependent enzymes,the O-O heterolysis yields a high-valent iron-oxo species,which is capable of performing a two-electron oxidation chemistry on various organic substrates.For the other two families of enzymes(extradiol dioxygenases and Rieske dioxygenases)the substrate oxidation and the O-O bond cleavage are found to be coupled.In the extradiol dioxygenases the product of the O-O bond cleavage is a ferric iron with an oxy-substrate with a mixture of radical and anionic character,which is essential for the selectivity of the catechol cleavage.
机译：带有B3LYP杂合功能的密度泛函理论已被用于研究单核非血红素铁酶的四个家族的双氧激活机制：α-酮酸依赖性双加氧酶，四氢生物蝶呤依赖性羟化酶，雌二醇双加氧酶和Rieske双加氧酶。具有一个共同的活性位点，其中亚铁离子与两个组氨酸和一个羧酸根基团（天冬氨酸或谷氨酸）配位。与血红素相比，这种弱磁场环境总是导致高自旋基态。在活性位点之外具有电子源的里氏双加氧酶，双氧活化过程经历了桥联过氧化物的形成，然后经历OO键裂解，最终导致O_2的四电子还原-在四氢生物蝶呤的情况下-和α-酮酸依赖性酶，OO杂解产生高价的铁-氧代物质，能够执行两电子在各种有机底物上的氧化化学反应。对于另外两个酶家族（extradiol双加氧酶和Rieske双加氧酶），发现底物氧化和OO键断裂是耦合的。带有带有自由基和阴离子特性混合物的氧底物，这对邻苯二酚裂解的选择性至关重要。

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