Oxidation of Pyrrole by Dehaloperoxidase-Hemoglobin: Chemoenzymatic Synthesis of Pyrrolin-2-Ones.
Oxidation of Pyrrole by Dehaloperoxidase-Hemoglobin: Chemoenzymatic Synthesis of Pyrrolin-2-Ones.
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DOI：
10.1039/c7cy00781g
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发表时间：
2017
影响因子：
5
通讯作者：
Ghiladi RA
中科院分区：
文献类型：
--
作者：
McCombs NL;Smirnova T;Ghiladi RA
在功能化单体吡咯的合成中使用氧化还原酶作为生物催化剂一直是一个挑战，这是由于许多因素中不希望的聚吡咯的形成。在这里，我们研究了脱卤过氧化物酶 (DHP)（来自四肢多毛动物 Amphitrite ornata 的体腔血红蛋白）作为该酶的一类新底物催化 H2O2 依赖性吡咯氧化的能力。在需氧和厌氧条件下，观察到所有使用的化合物（吡咯、N-甲基吡咯、2-甲基吡咯、3-甲基吡咯和2,5-二甲基吡咯）的底物氧化。使用吡咯作为代表性底物，仅观察到单一氧化产物4-吡咯啉-2-酮，并且值得注意的是没有形成聚吡咯。该催化球蛋白的所有三种生物相关氧化态均可引发反应性：三价铁、亚铁和含氧亚铁。同位素标记研究确定 4-pyrrolin-2-one 产品中的 O 原子完全来自 H2O2，这表明了过氧化酶机制。与这一观察结果一致，单混合和双混合停流紫外-可见光谱研究支持化合物I，但不支持化合物ES或II，作为参与吡咯氧化的催化相关的ferry1中间体。提出将二价氧亲电加成至吡咯作为氧原子转移的机制。结果证明了脱卤过氧化物酶具有广泛的化学反应活性，并为将 DHP 确立为多功能珠蛋白并作为生物催化剂进行实际应用提供了进一步的证据。使用脱卤过氧化物酶的生物催化方法可催化吡咯依赖 H2O2 的氧化反应生成 4-吡咯啉-2-酮，并且值得注意的是不会形成聚吡咯。
The use of oxidoreductases as biocatalysts in the syntheses of functionalized, monomeric pyrroles has been a challenge owing to, among a number of factors, undesired polypyrrole formation. Here, we have investigated the ability of dehaloperoxidase (DHP), the coelomic hemoglobin from the terebellid polychaete Amphitrite ornata, to catalyze the H2O2-dependent oxidation of pyrroles as a new class of substrate for this enzyme. Substrate oxidation was observed for all compounds employed (pyrrole, N-methylpyrrole, 2-methylpyrrole, 3-methylpyrrole and 2,5-dimethylpyrrole) under both aerobic and anaerobic conditions. Using pyrrole as a representative substrate, only a single oxidation product, 4-pyrrolin-2-one, was observed, and notably without formation of polypyrrole. Reactivity could be initiated from all three biologically relevant oxidation states for this catalytic globin: ferric, ferrous and oxyferrous. Isotope labeling studies determined that the O-atom incorporated into the 4-pyrrolin-2-one product was derived exclusively from H2O2, indicative of a peroxygenase mechanism. Consistent with this observation, single- and double-mixing stopped-flow UV-visible spectroscopic studies supported Compound I, but not Compounds ES or II, as the catalytically-relevant ferryl intermediate involved in pyrrole oxidation. Electrophilic addition of the ferryl oxygen to pyrrole is proposed as the mechanism of O-atom transfer. The results demonstrate the breadth of chemical reactivity afforded by dehaloperoxidase, and provide further evidence for establishing DHP as a multifunctional globin with practical applications as a biocatalyst. A biocatalytic approach using the enzyme dehaloperoxidase catalyzes the H2O2-dependent oxidation of pyrrole to 4-pyrrolin-2-one and notably without polypyrrole formation.