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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

07/15/1996

Pubmed ID

8713085

Pubmed Central ID

PMC1217522

DOI

10.1042/bj3170557

Scopus ID

2-s2.0-0030016330 (requires institutional sign-in at Scopus site)   16 Citations

Abstract

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 DJ

Author

Brian Bennett D.Phil. Professor and Chair in the Physics department at Marquette University




MESH terms used to index this publication - Major topics in bold

Amino Acid Sequence
Ferricyanides
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