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首页> 外文期刊>Biochemistry >Fluoride-Dependent Conversion of Organic Compounds Mediated by ManganesePeroxidases in the Absence of Mn~(2+) Ions
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Fluoride-Dependent Conversion of Organic Compounds Mediated by ManganesePeroxidases in the Absence of Mn~(2+) Ions

机译：Mn〜（2+）离子存在下锰过氧化物酶介导的有机化合物的氟依赖性转化

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摘要

Manganese peroxidase generally mediates the oxidation of Mn~(2+) to Mn~(3+) with H_2O_2 as an oxidant. Several manganese peroxidases purified from different lignin-degrading fungi were found to mediate a fluoride-dependent conversion of organic substrates such as monochlorodimedone or 2,6-dimethoxyphenol in the absence of manganese ions. Using the manganese peroxidase MnP-1 from Bjerkandera adusta strain Udl, these fluoride-dependent reactions were studied with respect to different substrates converted, reaction products, and kinetic properties to shed some light on the reaction mechanism of manganese peroxidase. The analysis of the reaction products formed from monochlorodimedone and 2,6-dimethoxyphenol showed that the substrates were oxidized rather than fluorinated. The addition of fluoride to MnP-1 resulted in altered absorption spectra, indicating a coordinative binding of fluoride or HF to the heme iron; the fluoride:heme stoichiometry was determined to be 1:1 and the KD value to be ～2.5 mM at pH 3.4. The high K_D value indicates weak binding of fluoride to the heme. Fluoride appeared to act as a partially competitive inhibitor with respect to hydrogen peroxide for binding to the heme as the sixth ligand. From the findings, a putative model for the fluoride-dependent reaction was developed. The data were interpreted to indicate that changes of the reaction center of manganese peroxidase as, for example, caused by fluoride binding may lead to the oxidation of organic compounds in the absence of manganese by opening a long-range electron transfer pathway.
机译：锰过氧化物酶通常以H_2O_2为氧化剂介导Mn〜（2+）氧化为Mn〜（3+）。发现从不同的木质素降解真菌纯化的几种锰过氧化物酶在不存在锰离子的情况下介导氟化物依赖性的有机底物如一氯二甲酮或2,6-二甲氧基苯酚的转化。使用来自Bjerkandera adusta菌株Udl的锰过氧化物酶MnP-1，针对转化的不同底物，反应产物和动力学性质研究了这些氟依赖性反应，以阐明锰过氧化物酶的反应机理。由一氯二甲酮和2，6-二甲氧基苯酚形成的反应产物的分析表明，底物被氧化而不是被氟化。在MnP-1中添加氟化物会导致吸收光谱发生变化，表明氟化物或HF与血红素铁的配位结合。在pH 3.4时，测定的氟化物：血红素化学计量比为1：1，KD值为〜2.5 mM。高的K_D值表明氟化物与血红素的结合较弱。氟化物似乎对过氧化氢起部分竞争性抑制剂的作用，以与作为第六配体的血红素结合。从发现中，开发了氟依赖反应的假定模型。数据被解释为表明，例如由于氟化物结合引起的锰过氧化物酶反应中心的变化可能会通过打开长程电子转移途径而导致在不存在锰的情况下氧化有机化合物。

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