Mitochondrial complex I and mitochondrial complex II (Complex I (for NADH:ubiquinone oxidoreductase), Complex II (for succinate dehydrogenase))

Mitochondrial complex I (NADH:ubiquinone oxidoreductase) is the first and largest enzyme of the mitochondrial electron transport chain, catalyzing electron transfer from NADH to ubiquinone coupled to translocation of protons across the mitochondrial inner membrane, thereby supporting ATP synthesis and cellular energy metabolism. Malfunction of complex I is linked to a wide spectrum of human diseases, including neurodegeneration and mitochondrial myopathies. Mitochondrial complex II (succinate dehydrogenase) is the only enzyme that participates in both the tricarboxylic acid (TCA) cycle and the electron transport chain. It catalyzes the oxidation of succinate to fumarate and transfers electrons to ubiquinone without translocating protons, making it unique among respiratory complexes. Deficiencies or mutations in complex II are linked to certain cancers and metabolic diseases. Note: For structured data representation, these two complexes should be stored and handled as separate and specific targets rather than a single entity.

Other names

Complex I: NADH:ubiquinone oxidoreductaseComplex I: NADH dehydrogenaseComplex I: Type I NADH dehydrogenaseComplex II: Succinate dehydrogenaseComplex II: succinate:ubiquinone oxidoreductase

Inhibition of electron transfer from NADH to ubiquinone (Complex I inhibitors); Decreased ATP production; increased ROS production (especially for some inhibitors); Inhibition of succinate oxidation/electron entry into the chain (Complex II inhibitors).