Unraveling proton-coupled electron transfer in cofactor-free oxidases- and oxygenases-catalyzed oxygen activation: a theoretical view

Oxygen plays a crucial role in the metabolism of non-anaerobic organisms. However, understanding the detailed process of how triplet oxygen participates in the enzymatic oxidation of organic compounds involved in life processes is still lacked. Noteworthy, recent studies have found that cofactor-free oxidases- and oxygenases-catalyzed activation of oxygen through the proton-coupled electron transfer (PCET), which is significantly different from the previously proposed single electron transfer (SET) mechanism. Herein, we have summarized recent advances in the general mechanism of catalytic activation reactions of triplet oxygen by these enzymes. We believe that this review not only helps people deeply understand the metabolic processes involved in oxygen in organisms, but also provides valuable theoretical reference data for designing more efficient enzyme mutants for treating diseases and handling environmental pollution in the future.