title: Incorporation of molybdenum in rubredoxin: models for mononuclear molybdenum enzymes.
abstract: Molybdenum is found in the active site of enzymes usually coordinated by one or two pyranopterin molecules. Here, we mimic an enzyme with a mononuclear molybdenum-bis pyranopterin center by incorporating molybdenum in rubredoxin. In the molybdenum-substituted rubredoxin, the metal ion is coordinated by four sulfurs from conserved cysteine residues of the apo-rubredoxin and two other exogenous ligands, oxygen and thiol, forming a Mo((VI))-(S-Cys)4(O)(X) complex, where X represents -OH or -SR. The rubredoxin molybdenum center is stabilized in a Mo(VI) oxidation state, but can be reduced to Mo(IV) via Mo(V) by dithionite, being a suitable model for the spectroscopic properties of resting and reduced forms of molybdenum-bis pyranopterin-containing enzymes. Preliminary experiments indicate that the molybdenum site built in rubredoxin can promote oxo transfer reactions, as exemplified with the oxidation of arsenite to arsenate.
authors.affiliation: UCIBIO, REQUIMTE, Departamento Química, Faculdade de Ciências e Tecnologia, Universidade Nova de Lisboa, 2829-516, Caparica, Portugal.
authors.forename: Biplab K
authors.initials: BK
authors.lastname: Maiti
authors.forename: Luisa B
authors.initials: LB
authors.lastname: Maia
authors.forename: Célia M
authors.initials: CM
authors.lastname: Silveira
authors.forename: Smilja
authors.initials: S
authors.lastname: Todorovic
authors.forename: Cintia
authors.initials: C
authors.lastname: Carreira
authors.forename: Marta S P
authors.initials: MS
authors.lastname: Carepo
authors.forename: Raquel
authors.initials: R
authors.lastname: Grazina
authors.forename: Isabel
authors.initials: I
authors.lastname: Moura
authors.forename: Sofia R
authors.initials: SR
authors.lastname: Pauleta
authors.forename: José J G
authors.initials: JJ
authors.lastname: Moura
mesh_terms: D055664:Electrochemical Techniques; D004578:Electron Spin Resonance Spectroscopy; D015394:Molecular Structure; D008982:Molybdenum / Q000737:chemistry / Q000378:metabolism*; D010088:Oxidoreductases / Q000737:chemistry / Q000378:metabolism*; D012416:Rubredoxins / Q000737:chemistry / Q000378:metabolism*
chemical_list: D012416:Rubredoxins; D008982:Molybdenum; D010088:Oxidoreductases