ABSTRACT
In this chapter, we summarize our current understanding of the structure and function of particulate methane monooxygenase (pMMO), a tantalizing enzyme found in methanotrophic bacteria that nature has created to mediate the facile conversion of methane to methanol at room temperature and under ambient pressures of air. We focus on the catalytic site of the enzyme, and show that it consists of a unique CuICuICuI tricopper cluster, which upon activation by dioxygen harnesses a highly reactive “singlet oxene” that can be directly inserted across a C-H bond of the hydrocarbon substrate in the transition state of the complex formed during the reaction of the substrate with the tricopper cluster. The oxidation of methane to methanol is dif-cult chemistry, as the C-H bond in methane is extremely inert. To accomplish this task efciently, nature has apparently invented new chemistry and exploited it for this difcult chemical transformation. Armed with these new chemical principles, we have designed and synthesized mimics of the active site of pMMO. We show that these models can mediate efcient methane oxidation in the laboratory as well.
