Structural investigation of the molybdenum site of the periplasmic nitrate reductase from Thiosphaera pantotropha by X-ray absorption spectroscopy. Biochem J 1996 Jul 15;317 ( Pt 2)(Pt 2):557-63
Date
07/15/1996Pubmed ID
8713085Pubmed Central ID
PMC1217522DOI
10.1042/bj3170557Scopus ID
2-s2.0-0030016330 (requires institutional sign-in at Scopus site) 16 CitationsAbstract
The molybdenum centre of the periplasmic respiratory nitrate reductase from the denitrifying bacterium Thiosphaera pantotropha has been probed using molybdenum K-edge X-ray absorption spectroscopy. The optimum fit of the Mo(VI) EXAFS suggests two ==O, three -S- and either a fourth -S- or an -O-/-N- as molybdenum ligands in the ferricyanide-oxidized enzyme. Three of the -S- ligands are proposed to be the two sulphur atoms of the molybdopterin dithiolene group and Cys-181. Comparison of the EXAFS of the ferricyanide-oxidized enzyme with that of a nitrate-treated sample containing 30% Mo(V) suggests that the Mo(VI)-->Mo(V) reduction is accompanied by conversion of one ==O to -O-. The best fit to the Mo(IV) EXAFS of dithionite-reduced enzyme was obtained using one ==O, one -O- and four -S-/-Cl ligands. The periplasmic nitrate reductase molybdenum co-ordination environment in both the Mo(VI) and Mo(IV) oxidation states is distinct from that found in the membrane-bound respiratory nitrate reductase.
Author List
Bennett B, Charnock JM, Sears HJ, Berks BC, Thomson AJ, Ferguson SJ, Garner CD, Richardson DJAuthor
Brian Bennett D.Phil. Professor and Chair in the Physics department at Marquette UniversityMESH terms used to index this publication - Major topics in bold
Amino Acid SequenceFerricyanides
Fourier Analysis
Gram-Negative Chemolithotrophic Bacteria
Ligands
Metalloproteins
Models, Chemical
Molecular Sequence Data
Molybdenum
Nitrate Reductase
Nitrate Reductases
Nitrates
Oxidation-Reduction
Sequence Homology, Amino Acid
Spectrum Analysis
X-Rays