Methane monooxygenases (MMOs) mediate the facile conversion of methane into methanol in methanotrophic bacteria with high efficiency under ambient conditions. Because the selective oxidation of methane is extremely challenging, there is considerable interest in understanding how these enzymes carry out this difficult chemistry. The impetus of these efforts is to learn from the microbes to develop a biomimetic catalyst to accomplish the same chemical transformation. Here, we review the progress made over the past two to three decades toward delineating the structures and functions of the catalytic sites in two MMOs: soluble methane monooxygenase (sMMO) and particulate methane monooxygenase (pMMO). sMMO is a water-soluble three-component protein complex consisting of a hydroxylase with a nonheme diiron catalytic site; pMMO is a membrane-bound metalloenzyme with a unique tricopper cluster as the site of hydroxylation. The metal cluster in each of these MMOs harnesses O₂ to functionalize the C—H bond using different chemistry. We highlight some of the common basic principles that they share. Finally, the development of functional models of the catalytic sites of MMOs is described. These efforts have culminated in the first successful biomimetic catalyst capable of efficient methane oxidation without overoxidation at room temperature.

中文翻译：

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烷烃氧化：甲烷单加氧酶，相关酶及其仿生物质

甲烷单加氧酶（MMO）在环境条件下高效地介导甲烷氧化菌中甲烷向甲醇的轻松转化。由于甲烷的选择性氧化极具挑战性，因此人们对了解这些酶如何进行这种困难的化学反应非常感兴趣。这些努力的动力是向微生物学习以开发仿生催化剂以完成相同的化学转化。在这里，我们回顾了过去两到三十年来在描述两种MMO中催化位点的结构和功能方面所取得的进展：可溶性甲烷单加氧酶（sMMO）和颗粒甲烷单加氧酶（pMMO）。sMMO是一种水溶性的三组分蛋白质复合物，由具有非血红素二铁催化位点的羟化酶组成；pMMO是一种膜结合的金属酶，具有独特的三铜簇作为羟基化位点。每个MMO中的金属簇都利用O₂使用不同的化学方法将CH键功能化。我们重点介绍了它们共享的一些通用基本原理。最后，描述了MMO催化位点的功能模型的开发。这些努力最终导致了第一个成功的仿生催化剂，该催化剂能够在室温下有效地甲烷氧化而不会发生过氧化。