Succinate-cytochrome c reductase: assessment of its value in the investigation of defects of the respiratory chain.
Defects of the respiratory chain are important causes of human disease and one of the most commonly used assays in the investigation of these patients is the measurement of succinate-cytochrome c reductase. However, this assay measures several components of the respiratory chain and the ability to detect a partial defect in one enzyme complex will depend on the amount of control exerted by that enzyme step on overall electron flux. We show that measurement of succinate-cytochrome c reductase activity may fail to detect partial defects of complex III and therefore is of limited diagnostic value in the identification of complex III defects. However, complex II is a major point of control of flux through succinate-cytochrome reductase and it is likely that measurement of the latter will detect defects of complex II.
Department of Child Health and Clinical Biochemistry, Medical School, University of Newcastle upon Tyne, UK.
R W
RW
Taylor
M A
MA
Birch-Machin
K
K
Bartlett
D M
DM
Turnbull
D000818:Animals; D003573:Cytochrome b Group / Q000032:analysis; D004579:Electron Transport; D042963:Electron Transport Complex II; D014450:Electron Transport Complex III / Q000032:analysis / Q000172:deficiency; D006801:Humans; D008314:Malonates / Q000494:pharmacology; D008931:Mitochondria, Muscle / Q000201:enzymology*; D017237:Mitochondrial Encephalomyopathies / Q000201:enzymology; D009097:Multienzyme Complexes / Q000032:analysis / Q000037:antagonists & inhibitors; D010088:Oxidoreductases / Q000032:analysis / Q000037:antagonists & inhibitors; D051381:Rats; D013384:Succinate Cytochrome c Oxidoreductase / Q000032:analysis*; D013385:Succinate Dehydrogenase / Q000032:analysis / Q000037:antagonists & inhibitors
D003573:Cytochrome b Group; D008314:Malonates; D009097:Multienzyme Complexes; C030290:malonic acid; D010088:Oxidoreductases; D013384:Succinate Cytochrome c Oxidoreductase; D042963:Electron Transport Complex II; D013385:Succinate Dehydrogenase; D014450:Electron Transport Complex III