Quinone reduction sites and the role of heme in succinate:quinone reductase. Studies in Bacillus subtilis and Paracoccus denitrificans
Succinate:quinone reductase (SQR) is an enzyme in the respiratory system of aerobic cells. SQR catalyzes two reactions, the oxidation of succinate to fumarate and the reduction of quinone to quinol. These reactions are coupled by electron transfer within the enzyme from the site of succinate oxidation to the site of quinone reduction. Some enzymes reduce ubiquinone (exergonic reaction) whereas oth