title: ATP-uncoupled, six-electron photoreduction of hydrogen cyanide to methane by the molybdenum-iron protein.
abstract: A detailed study of the eight-electron/eight-proton catalytic reaction of nitrogenase has been hampered by the fact that electron and proton flow in this system is controlled by ATP-dependent protein-protein interactions. Recent studies have shown that it is possible to circumvent the dependence on ATP through the use of potent small-molecule reductants or light-driven electron injection, but success has been limited to two-electron reductions of hydrazine, acetylene, or protons. Here we show that a variant of the molybdenum-iron protein labeled with a Ru-photosensitizer can support the light-driven, six-electron catalytic reduction of hydrogen cyanide into methane and likely also ammonia. Our findings suggest that the efficiency of this light-driven system is limited by the initial one- or two-electron reduction of the catalytic cofactor (FeMoco) to enable substrate binding, but the subsequent electron-transfer steps into the FeMoco-bound substrate proceed efficiently.
authors.affiliation: Department of Chemistry and Biochemistry, University of California, San Diego, La Jolla, 92093-0356, United States.
authors.forename: Lauren E
authors.initials: LE
authors.lastname: Roth
authors.forename: F Akif
authors.initials: FA
authors.lastname: Tezcan
mesh_terms: D000641:Ammonia / Q000378:metabolism; D016948:Azotobacter vinelandii / Q000737:chemistry / Q000201:enzymology* / Q000235:genetics / Q000378:metabolism; D006856:Hydrogen Cyanide / Q000378:metabolism*; D008697:Methane / Q000378:metabolism*; D008958:Models, Molecular; D008983:Molybdoferredoxin / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D010084:Oxidation-Reduction; D017354:Point Mutation; D011487:Protein Conformation
chemical_list: D008983:Molybdoferredoxin; D006856:Hydrogen Cyanide; D000641:Ammonia; D008697:Methane