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 3. S supports electron flux through Complex II (see SDH ) to CII-bound flavin adenine dinucleotide (FADH₂) to the Q-junction. 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. 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 (positive phase) to the negative phase with a P» ratio of 1.75 (P/O2 = 3.5).

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