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Mechanisms for Methane and Ammonia Oxidation by Particulate Methane Monooxygenase
The Journal of Physical Chemistry B ( IF 2.8 ) Pub Date : 2024-06-08 , DOI: 10.1021/acs.jpcb.4c01807 Per E M Siegbahn 1
The Journal of Physical Chemistry B ( IF 2.8 ) Pub Date : 2024-06-08 , DOI: 10.1021/acs.jpcb.4c01807 Per E M Siegbahn 1
Affiliation
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Particulate MMO (pMMO) catalyzes the oxidation of methane to methanol and also ammonia to hydroxylamine. Experimental characterization of the active site has been very difficult partly because the enzyme is membrane-bound. However, recently, there has been major progress mainly through the use of cryogenic electron microscopy (cryoEM). Electron paramagnetic resonance (EPR) and X-ray spectroscopy have also been employed. Surprisingly, the active site has only one copper. There are two histidine ligands and one asparagine ligand, and the active site is surrounded by phenyl alanines but no charged amino acids in the close surrounding. The present study is the first quantum chemical study using a model of that active site (CuD). Low barrier mechanisms have been found, where an important part is that there are two initial proton-coupled electron transfer steps to a bound O2 ligand before the substrate enters. Surprisingly, this leads to large radical character for the oxygens even though they are protonated. That result is very important for the ability to accept a proton from the substrates. Methods have been used which have been thoroughly tested for redox enzyme mechanisms.
中文翻译：
颗粒甲烷单加氧酶氧化甲烷和氨的机制
颗粒 MMO (pMMO) 催化甲烷氧化成甲醇，也催化氨氧化成羟胺。活性位点的实验表征非常困难，部分原因是酶是膜结合的。然而，最近主要通过低温电子显微镜（cryoEM）的使用取得了重大进展。电子顺磁共振（EPR）和X射线光谱也已被采用。令人惊讶的是，活性位点只有一个铜。有两个组氨酸配体和一个天冬酰胺配体，活性位点被苯丙氨酸包围，但附近没有带电氨基酸。本研究是第一个使用该活性位点 (Cu D ) 模型的量子化学研究。已经发现了低势垒机制，其中重要的部分是在底物进入之前有两个初始质子耦合电子转移步骤至结合的O 2配体。令人惊讶的是，即使氧被质子化，这也会导致氧具有很大的自由基特征。该结果对于从基底接受质子的能力非常重要。所使用的方法已经过氧化还原酶机制的彻底测试。
更新日期：2024-06-08
中文翻译：
颗粒甲烷单加氧酶氧化甲烷和氨的机制
颗粒 MMO (pMMO) 催化甲烷氧化成甲醇，也催化氨氧化成羟胺。活性位点的实验表征非常困难，部分原因是酶是膜结合的。然而，最近主要通过低温电子显微镜（cryoEM）的使用取得了重大进展。电子顺磁共振（EPR）和X射线光谱也已被采用。令人惊讶的是，活性位点只有一个铜。有两个组氨酸配体和一个天冬酰胺配体，活性位点被苯丙氨酸包围，但附近没有带电氨基酸。本研究是第一个使用该活性位点 (Cu D ) 模型的量子化学研究。已经发现了低势垒机制，其中重要的部分是在底物进入之前有两个初始质子耦合电子转移步骤至结合的O 2配体。令人惊讶的是，即使氧被质子化，这也会导致氧具有很大的自由基特征。该结果对于从基底接受质子的能力非常重要。所使用的方法已经过氧化还原酶机制的彻底测试。
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