Structural Investigation of the Molybdenum Site of the Periplasmic Nitrate Reductase from Thiosphaera pantotropha by X-ray Absorption Spectroscopy
Document Type
Article
Language
eng
Format of Original
7 p.
Publication Date
7-15-1996
Publisher
Portland Press Limited
Source Publication
Biochemical Journal
Source ISSN
0264-6021
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.
Recommended Citation
Bennett, Brian; Charnock, John M.; Sears, Heather J.; Berks, Ben C.; Thomson, Andrew J.; Ferguson, Stuart J.; Garner, C. David; and Richardson, David J., "Structural Investigation of the Molybdenum Site of the Periplasmic Nitrate Reductase from Thiosphaera pantotropha by X-ray Absorption Spectroscopy" (1996). Physics Faculty Research and Publications. 98.
https://epublications.marquette.edu/physics_fac/98
Comments
Biochemical Journal, Vol. 317, No. 2 (July 15, 1996): 557-563. DOI.
Brian Bennett was affiliated with the University of East Anglia at the time of publication.