Reactions of cytochrome c oxidase with sodium dithionite.
The reduction of cytochrome c oxidase (EC 1.9.3.1) by dithionite was investigated by stopped-flow spectrophotometry and flow-flash techniques in the presence of CO. Of the two haem groups present in the enzyme, that associated with cytochrome alpha is the first reduced. The second-order rate constants for reduction of a number of redox proteins (cytochrome c, stellacyanin and azurin) by the S2O4(2-) and SO2.- anions are reported, and the values are compared with those determined for cytochrome c oxidase. These results are discussed in terms of the accessibility and charge distribution of the electron-entry site of cytochrome c oxidase.
D004227:Dithionite / Q000378:metabolism*; D003576:Electron Transport Complex IV / Q000378:metabolism*; D007700:Kinetics; D008027:Light; D008667:Metalloproteins / Q000378:metabolism; D008956:Models, Chemical; D010084:Oxidation-Reduction; D013053:Spectrophotometry; D013447:Sulfites / Q000378:metabolism*
D008667:Metalloproteins; D013447:Sulfites; D004227:Dithionite; D003576:Electron Transport Complex IV