Succinate-cytochrome c reductase (SCR) (SCR)

Succinate-cytochrome c reductase (SCR) is an integrated multienzyme system located in the mitochondrial inner membrane, representing the coupled activities of Complex II (succinate:ubiquinone oxidoreductase) and Complex III (ubiquinol:cytochrome c oxidoreductase). [5, 8, 14] Its primary biological function is to catalyze the transfer of electrons from succinate to cytochrome c via the ubiquinone pool, a vital segment of the respiratory chain that supports the generation of a proton gradient for ATP synthesis. [12, 16] Genetic defects in the subunits composing this system are linked to mitochondrial encephalomyopathies, Leigh syndrome, and various cancers where the accumulation of succinate functions as a tumorigenic oncometabolite. [1, 11, 12] SCR is a significant target in toxicology for predicting drug-induced mitochondrial dysfunction, as many pharmaceutical agents and environmental toxins can inhibit its activity, leading to energy depletion and oxidative stress. [3, 8] Furthermore, it is targeted by experimental anticancer compounds known as mitocans, such as MKT-077, which aim to induce apoptosis in malignant cells by disrupting mitochondrial electron flux and increasing superoxide production. [4, 10, 15]

Other names

Succinate-cytochrome c oxidoreductaseComplex II-III systemSuccinate:cytochrome c oxidoreductaseSuccinate-ubiquinol-cytochrome c reductase

Inhibition of the integrated electron transfer from succinate to cytochrome c, disrupting the mitochondrial respiratory chain, reducing ATP production, and increasing the leakage of electrons to form reactive oxygen species.