Kinetics studies of the superoxide-mediated electron transfer reactions between rubredoxin-type proteins and superoxide reductases.
In 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 spirochete 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 kapp 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 kapp value of 108.8+/-12.0 min(-1), and was then assigned as the potential physiological electron donor in this organism.
REQUIMTE-Centro de Química Fina e Biotecnologia, Departamento de Química, Faculdade de Ciências e Tecnologia, Universidade Nova de Lisboa, 2829-516, Caparica, Portugal.
Françoise
F
Auchère
Sofia R
SR
Pauleta
Pedro
P
Tavares
Isabel
I
Moura
José J G
JJ
Moura
D000818:Animals; D001426:Bacterial Proteins / Q000737:chemistry / Q000235:genetics / Q000378:metabolism; D002417:Cattle; D045286:Desulfovibrio gigas / Q000201:enzymology; D016969:Desulfovibrio vulgaris / Q000201:enzymology; D004563:Electrochemistry; D004579:Electron Transport; D033862:Iron-Binding Proteins / Q000737:chemistry / Q000378:metabolism; D007506:Iron-Sulfur Proteins / Q000737:chemistry / Q000378:metabolism; D007700:Kinetics; D010088:Oxidoreductases / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism; D050862:Oxidoreductases Acting on Sulfur Group Donors / Q000737:chemistry / Q000378:metabolism; D012416:Rubredoxins / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism; D013053:Spectrophotometry; D013481:Superoxides / Q000737:chemistry* / Q000378:metabolism
D001426:Bacterial Proteins; D033862:Iron-Binding Proteins; D007506:Iron-Sulfur Proteins; D012416:Rubredoxins; D013481:Superoxides; C022220:desulforedoxin; D010088:Oxidoreductases; C121849:superoxide reductase; D050862:Oxidoreductases Acting on Sulfur Group Donors