Succinate pathway

high-resolution terminology - matching measurements at high-resolution

Succinate pathway

Description

S-pathway control, S, is achieved with succinate as the single substrate, an ETS-level 3 substrate: succinate-induced respiratory state; CII-linked; SRot; succinate alone. S supports electron flux through Complex II to CII-bound flavin adenine dinucleotide (FADH2) to Q. Inhibition of Complex I by rotenone (Rot; or amytal, piericidine) prevents accumulation of oxaloacetate which is a potent inhibitor of succinate dehydrogenase. After inhibition of CI by rotenone, 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 Complex II-linked substrate state is induced in mt-preparations by addition of succinate&rotenone (Complex I inhibitor). Succinate is the direct substrate of Complex II (succinate dehydrogenase). In CII-linked respiration, 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).

Abbreviation: S

Reference: Gnaiger 2014 MitoPathways - Chapter 4.1, Gnaiger 2000 Proc Natl Acad Sci U S A

MitoPedia concepts: Respiratory state, SUIT state 

Succinate+rotenone, S(Rot). From Gnaiger 2014 MitoPathways.

SRot(L)

1. ~P/O2 ratio: Gnaiger 2000 Proc Natl Acad Sci U S A
2. O2k-Protocols: MiPNet12.11 MitoRespiration
3. Comparison with S alone, CI&II, and H₂O₂ production: Makrecka-Kuka 2015 Biomolecules

SRot(P)

1. ~P/O2 ratio: Gnaiger 2000 Proc Natl Acad Sci U S A
2. O2k-Protocols: MiPNet12.11 MitoRespiration
3. Comparison with S alone CI&II, and H₂O₂ production: Makrecka-Kuka 2015 Biomolecules

SRot(E)

1. O2k-Protocols: MiPNet12.11 MitoRespiration
2. Comparison with CI-CI&II-CII SUIT protocol: Votion 2012 PLoS One
3. SUIT_RP1: SUIT_FNSGp(PGM)01_7Rot: 1PM 2D&Dc (&DcNADH) 3U 4Oct 5G 6S 7Rot 8Gp 9Ama 10Tm 11Azd

List of publications: S- or CII-linked pathway control

This list does not distinguish between substrate states for Succinate alone (without Rot) and SRot.