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Addressing Serine Lability in a Paramagnetic Dimethyl Sulfoxide Reductase Catalytic Intermediate

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journal contribution
posted on 10.06.2021, 23:13 by Khadanand KC, Jing Yang, Martin L. Kirk
Two new desoxo molybdenum­(V) complexes have been synthesized and characterized as models for the paramagnetic high-g split intermediate observed in the catalytic cycle of dimethyl sulfoxide reductase (DMSOR). Extended X-ray absorption fine structure (EXAFS) and electron paramagnetic resonance (EPR) data are used to provide new insight into the geometric and electronic structures of high-g split and other EPR-active type II/III DMSOR family enzyme forms. The results support a 6-coordinate [(PDT)2Mo­(OH)­(OSer)] structure (PDT = pyranopterin dithiolene) for a high-g split with four S donors from two PDT ligands, a coordinated hydroxyl ligand, and a serinate O donor. This geometry orients the redox orbital toward the substrate access channel for the two-electron reduction of substrates.

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