Kinetics studies of the superoxide-mediated electron transfer reactions between rubredoxin-type proteins and superoxide reductases,
Auchere, F., Pauleta S. R., Tavares P., Moura I., and Moura J. J. G.
, JOURNAL OF BIOLOGICAL INORGANIC CHEMISTRY, Jul, Volume {11}, Number {4}, p.{433-444}, (2006)
AbstractIn this work we present a kinetic study of the superoxide-mediated electron transfer reactions between rubredoxin-type proteins and members of the three different classes of superoxide reductases (SORs). SORs from the sulfate-reducing bacteria Desulfovibrio vulgaris (Dv) and D. gigas (Dg) were chosen as prototypes of classes I and II, respectively, while SOR from the syphilis spyrochete Treponema pallidum (Tp) was representative of class III. Our results show evidence for different behaviors of SORs toward electron acceptance, with a trend to specificity for the electron donor and acceptor from the same organism. Comparison of the different k (app) values, 176.9 +/- 25.0 min(-1) in the case of the Tp/Tp electron transfer, 31.8 +/- 3.6 min(-1) for the Dg/Dg electron transfer, and 6.9 +/- 1.3 min(-1) for Dv/Dv, could suggest an adaptation of the superoxide-mediated electron transfer efficiency to various environmental conditions. We also demonstrate that, in Dg, another iron-sulfur protein, a desulforedoxin, is able to transfer electrons to SOR more efficiently than rubredoxin, with a k (app) value of 108.8 +/- 12.0 min(-1), and was then assigned as the potential physiological electron donor in this organism.
Metalloenzymes of the denitrification pathway,
Tavares, P., Pereira A. S., Moura J. J. G., and Moura I.
, Journal Of Inorganic Biochemistry, Dec, Volume {100}, Number {12}, p.{2087-2100}, (2006)
AbstractDenitrification, or dissimilative nitrate reduction, is an anaerobic process used by some bacteria for energy generation. This process is important in many aspects, but its environmental implications have been given particular relevance. Nitrate accumulation and release of nitrous oxide in the atmosphere due to excess use of fertilizers in agriculture are examples of two environmental problems where denitrification plays a central role. The reduction of nitrate to nitrogen gas is accomplished by four different types of metalloenzymes in four simple steps: nitrate is reduced to nitrite, then to nitric oxide, followed by the reduction to nitrous oxide and by a final reduction to dinitrogen. In this manuscript we present a concise updated review of the bioinorganic aspects of denitrification. (c) 2006 Elsevier Inc. All rights reserved.
Nitric oxide reductase: Direct electrochemistry and electrocatalytic activity,
Cordas, Cristina M., Pereira Alice S., Martins Carlos E., Timoteo Cristina G., Moura Isabel, Moura Jose J. G., and Tavares Pedro
, Chembiochem, Dec, Volume {7}, Number {12}, p.{1878-1881}, (2006)
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