Open AccessAddressing Ligand-Based Redox in Molybdenum-Dependent Methionine Sulfoxide Reductase
Author(s) -
Laura Ingersol,
Jing Yang,
Khadanand Kc,
Amrit Pokhrel,
Andrei V. Astashkin,
Joël H. Weiner,
Christopher D. Johnston,
Martin L. Kirk
Publication year - 2020
Publication title -
journal of the american chemical society
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 7.115
H-Index - 612
eISSN - 1520-5126
pISSN - 0002-7863
DOI - 10.1021/jacs.9b11762
Subject(s) - chemistry , ligand (biochemistry) , electron paramagnetic resonance , redox , molybdenum , methionine sulfoxide , methionine sulfoxide reductase , context (archaeology) , thioredoxin reductase , electron transfer , sulfoxide , photochemistry , crystallography , inorganic chemistry , methionine , enzyme , organic chemistry , thioredoxin , biochemistry , nuclear magnetic resonance , receptor , amino acid , paleontology , physics , biology
A combination of pulsed EPR, CW EPR, and X-ray absorption spectroscopies has been employed to probe the geometric and electronic structure of the E. coli periplasmic molybdenum-dependent methionine sulfoxide reductase (MsrP). 17 O and 1 H pulsed EPR spectra show that the as-isolated Mo(V) enzyme form does not possess an exchangeable H 2 O/OH - ligand bound to Mo as found in the sulfite oxidizing enzymes of the same family. The nature of the unusual CW EPR spectrum has been re-evaluated in light of new data on the MsrP-N45R variant and related small-molecule analogues of the active site. These data point to a novel "thiol-blocked" [(PDT)Mo V O(S Cys )(thiolate)] - structure, which is supported by new EXAFS data. We discuss these new results in the context of ligand-based and metal-based redox chemistry in the enzymatic oxygen atom transfer reaction.