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Succinate dehydrogenase
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<p>Succinate dehydrogenase (SDH) or succinate-coenzyme Q reductase (SQR) or respiratory complex II is an <a href="/facts/Enzyme/DSI1Fh7y">enzyme</a> complex, found in many <a href="/facts/Bacterial/wC8xSCsU">bacterial</a> <a href="/facts/Cell_(biology)/bLM9UQvy">cells</a> and in the <a href="/facts/Inner_mitochondrial_membrane/IJIE4o0h">inner mitochondrial membrane</a> of <a href="/facts/Eukaryotes/SkwyPLMA">eukaryotes</a>. It is the only enzyme that participates in both the <a href="/facts/Citric_acid_cycle/EGJL9NXP">citric acid cycle</a> and <a href="/facts/Oxidative_phosphorylation/en2l08P9">oxidative phosphorylation</a>. Histochemical analysis showing high succinate dehydrogenase in muscle demonstrates high mitochondrial content and high oxidative potential. </p><p>In step 6 of the <a href="/facts/Citric_acid_cycle/EGJL9NXP">citric acid cycle</a>, SQR <a href="/facts/Catalyzes/LPBS7TQC">catalyzes</a> the <a href="/facts/Oxidation/Pyd5RVcj">oxidation</a> of <a href="/facts/Succinate/v3KJqrQC">succinate</a> to <a href="/facts/Fumarate/VDecBfLQ">fumarate</a> with the <a href="/facts/Redox/Pyd5RVcj">reduction</a> of <a href="/facts/Ubiquinone/xoeh3R3e">ubiquinone</a> to <a href="/facts/Ubiquinol/tUfSbf5I">ubiquinol</a>. This occurs in the inner mitochondrial <a href="/facts/Biological_membrane/ljBsfK4r">membrane</a> by <a href="/facts/Coupling/JDHEKQYn">coupling</a> the two reactions together. </p>