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PM-pathway control state

From Bioblast
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high-resolution terminology - matching measurements at high-resolution


PM-pathway control state

Description

PM

PM: Pyruvate & Malate.

MitoPathway control state: NADH Electron transfer-pathway state

SUIT protocol: 1PM;2D;3U;4G;5S;6Oct;7Rot;8Gp- - SUIT_RP1

Upstream of the NAD-junction, 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 (Ξ±-ketoglutarate) is formed from isocitrate (isocitrate dehydrogenase).

Abbreviation: PM

Reference: Gnaiger 2020 BEC MitoPathways

Gnaiger 2020 BEC MitoPathways

PML

With PM as N-substrates, LEAK respiration L can be evaluated in the following SUIT protocols:


PMP

With PM as N-substrates, OXPHOS capacity P can be evaluated in the following SUIT protocols:

PME

With PM as N-substrates, ET capacity E can be evaluated in the following SUIT protocols:


Linear coupling control in the N-pathway control state: L β†’ P β†’ E

  • P-L
P-L control efficiency, jP-L = (P-L)/P = 1-L/P, is measured in the N-pathway state, with defined coupling sites (CI, CIII, CIV).
  • P-E
CCCP is titrated stepwise to maximum flux, to evaluate limitation of OXPHOS by the phosphorylation system, expressed as the E-P control efficiency jE-P = (E-P)/E = 1-P/E.
If jE-P>0, then the E-L coupling efficiency rather than the P-L control efficiency is the proper expression of coupling, jE-L = (E-L)/E = 1-L/E.


Discussion

The Pyruvate anaplerotic pathway control state (pyruvate alone) is not an ET-pathway competent substrate state in most mt-preparations, since acetyl-CoA accumulates without the co-substrate (oxaloacetate) of citrate synthase.
The Malate-anaplerotic pathway control state (M alone) is not an ET-pathway competent substrate state in many mt-preparations, since oxaloacetate accumulates without the co-substrate (acetyl-CoA) of citrate synthase.


MitoPedia concepts: SUIT state