TY - JOUR
T1 - EPR and redox properties of periplasmic nitrate reductase from Desulfovibrio desulfuricans ATCC 27774
AU - González, Pablo J.
AU - Rivas, María G.
AU - Brondino, Carlos D.
AU - Bursakov, Sergey A.
AU - Moura, Isabel
AU - Moura, José J. G.
N1 - P.J.G. (SFRH/BD/10825/2002) and M.G.R. (SFRH/BD/10784/2002) thank FCT for a fellowship grant. C.D.B. and J.J.G.M. thank SECYT (Argentina) and GRICES (Portugal) for a bi-national grant. This work was supported by projects EC HPRN-CT-1999-00084, POCTI/1999/BME/35078, and POCTI/ 1999/BME/36152 in Portugal, and SEPCYT:PICT 2003-06-13872, CONICET PIP 02559/2000, and CAI+D-UNL in Argentina. C.D.B. is a member of CONICET-Argentina.
PY - 2006/7/1
Y1 - 2006/7/1
N2 - Nitrate reductases are enzymes that catalyze the conversion of nitrate to nitrite. We report here electron paramagnetic resonance (EPR) studies in the periplasmic nitrate reductase isolated from the sulfate-reducing bacteria Desulfovibrio desulfuricans ATCC 27774. This protein, belonging to the dimethyl sulfoxide reductase family of mononuclear Mo-containing enzymes, comprises a single 80-kDa subunit and contains a Mo bis(molybdopterin guanosine dinucleotide) cofactor and a [4Fe-4S] cluster. EPR-monitored redox titrations, carried out with and without nitrate in the potential range from 200 to -500 mV, and EPR studies of the enzyme, in both catalytic and inhibited conditions, reveal distinct types of Mo(V) EPR-active species, which indicates that the Mo site presents high coordination flexibility. These studies show that nitrate modulates the redox properties of the Mo active site, but not those of the [4Fe-4S] center. The possible structures and the role in catalysis of the distinct Mo(V) species detected by EPR are discussed.
AB - Nitrate reductases are enzymes that catalyze the conversion of nitrate to nitrite. We report here electron paramagnetic resonance (EPR) studies in the periplasmic nitrate reductase isolated from the sulfate-reducing bacteria Desulfovibrio desulfuricans ATCC 27774. This protein, belonging to the dimethyl sulfoxide reductase family of mononuclear Mo-containing enzymes, comprises a single 80-kDa subunit and contains a Mo bis(molybdopterin guanosine dinucleotide) cofactor and a [4Fe-4S] cluster. EPR-monitored redox titrations, carried out with and without nitrate in the potential range from 200 to -500 mV, and EPR studies of the enzyme, in both catalytic and inhibited conditions, reveal distinct types of Mo(V) EPR-active species, which indicates that the Mo site presents high coordination flexibility. These studies show that nitrate modulates the redox properties of the Mo active site, but not those of the [4Fe-4S] center. The possible structures and the role in catalysis of the distinct Mo(V) species detected by EPR are discussed.
KW - Dimethyl sulfoxide reductase family
KW - Electron paramagnetic resonance
KW - Molybdenum-containing enzymes
KW - Periplasmic nitrate reductase
KW - Redox titration
UR - http://www.scopus.com/inward/record.url?scp=33745407695&partnerID=8YFLogxK
U2 - 10.1007/s00775-006-0110-0
DO - 10.1007/s00775-006-0110-0
M3 - Article
C2 - 16791644
AN - SCOPUS:33745407695
SN - 0949-8257
VL - 11
SP - 609
EP - 616
JO - JBIC Journal of Biological Inorganic Chemistry
JF - JBIC Journal of Biological Inorganic Chemistry
IS - 5
ER -