PM-pathway control state

high-resolution terminology - matching measurements at high-resolution

PM-pathway control state

Description

PM, CI-linked pathway: Pyruvate (P) is oxidatively decarboxylated to acetyl-CoA and CO₂, yielding NADH catalyzed by pyruvate dehydrogenase. Malate (M) is oxidized to oxaloacetate by mt-malate dehydrogenase located in the mitochondrial matrix. Condensation of oxaloacate with acetyl-CoA yields citrate (citrate synthase). 2-oxoglutarate (α-ketoglutarate) is formed from isocitrate (isocitrate dehydrogenase).

Abbreviation: PM

Reference: Gnaiger 2014 MitoPathways - Chapter 3.2

MitoPedia topics: "Respiratory substrate-coupling state" is not in the list (Enzyme, Medium, Inhibitor, Substrate and metabolite, Uncoupler, Sample preparation, Permeabilization agent, EAGLE, MitoGlobal Organizations, MitoGlobal Centres, ...) of allowed values for the "MitoPedia topic" property. Respiratory substrate-coupling state"Respiratory substrate-coupling state" is not in the list (Enzyme, Medium, Inhibitor, Substrate and metabolite, Uncoupler, Sample preparation, Permeabilization agent, EAGLE, MitoGlobal Organizations, MitoGlobal Centres, ...) of allowed values for the "MitoPedia topic" property. 

PM(L)

• SUIT-RP1: 1PM 2D 2c (2NADH) 3U 4Oct 5G 6S 7Rot 8Gp 9Ama 10Tm

PM(P)

• SUIT-RP1: 1PM 2D 2c (2NADH) 3U 4Oct 5G 6S 7Rot 8Gp 9Ama 10Tm

PM(E)

• SUIT-RP1: 1PM 2D 2c (2NADH) 3U 4Oct 5G 6S 7Rot 8Gp 9Ama 10Tm

CI-linked linear coupling control: L – P - E

• L - P

OXPHOS coupling efficiency (P-L or ≈P control factor), j_≈P = ≈P/P = (P-L)/P = 1-L/P, is measured in the CI-linked substrate state, with defined coupling sites (CI, CIII, CIV) and at high flux.

• P - E

CCCP is titrated stepwise to maximum flux, to evaluate limitation of OXPHOS by the phosphorylation system, expressed as the apparent excess E-P capacity factor (E-P coupling control factor), j_ExP = (E-P)/E = 1-P/E. If j_ExP>0, then the ETS coupling efficiency rather than the OXPHOS coupling efficiency is the proper expression of coupling, j_≈E = ≈E/E = (E-L)/E = 1-L/E.

Discussion

• Pyruvate alone is not an ETS competent substrate state in most mt-preparations, since acetyl-CoA accumulates without the co-substrate (oxaloacetate) of citrate synthase.
• Malate alone is not an ETS competent substrate state in many mt-preparations, since oxaloacetate accumulates without the co-substrate (acetyl-CoA) of citrate synthase.