Talk:Succinate pathway

The succinate-linked respiration or S-pathway (succinate-induced respiratory state; previously used nomenclature: CII-linked respiration; SRot; see [Gnaiger 2009 Int J Biochem Cell Biol]) is achieved with succinate (S) as the single substrate, at ET-pathway-level pathway level 3. S supports electron flux through mitochondrial Complex II (succinate dehydrogenase) to CII-bound flavin adenine dinucleotide (FADH2) to Q. Inhibition of Complex I (CI) by rotenone (Rot; or amytal, piericidine) prevents accumulation of oxaloacetate which is a potent inhibitor of succinate dehydrogenase. After inhibition of CI by Rot, the NADH-linked dehydrogenases become inhibited by the redox shift from NAD+ to NADH. Succinate dehydrogenase is activated by succinate and ATP, which explains in part the time-dependent increase of respiration in isolated mitochondria after addition of rotenone (first), succinate and ADP.

The S-pathway is induced in mt-preparations by addition of succinate&rotenone (Complex I inhibitor). Succinate is the direct substrate of Complex II (succinate dehydrogenase). In this case, only Complex III and Complex IV are involved in pumping protons from the matrix (P-phase) to the N-phase with a ~P/O ratio of 1.75 (P/O2 = 3.5).

~The changes are in bold. Bastosa (talk) 14:36, 24 July 2018 (CEST)