Metabolic control variable

high-resolution terminology - matching measurements at high-resolution

Metabolic control variable

Description

A metabolic control variable X causes the transition between a background state Y (background rate Y_X) and a reference state Z (reference rate Z_X). X may be a stimulator or activator of flux, inducing the step change from background to reference steady state (Y to Z). Alternatively, X may be an inhibitor of flux, absent in the reference state but present in the background state (step change from Z to Y).

Abbreviation: X

Reference: Flux control efficiency

Communicated by Gnaiger E (2013-08-03) last update 2020-11-10.

Keywords

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  The Blue Book 2020
  

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  OXPHOS-, ROUTINE-, ET-, and LEAK states; respiratory capacities (P, R, E, L) corrected for residual oxygen consumption Rox.

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  4-compartmental OXPHOS model. (1) ET capacity E of the noncoupled electron transfer system ETS. OXPHOS capacity P is partitioned into (2) the dissipative LEAK component L, and (3) ADP-stimulated P-L net OXPHOS capacity. (4) If P-L is kinetically limited by a low capacity of the phosphorylation system to utilize the protonmotive force pmF, then the apparent E-P excess capacity is available to drive coupled processes other than phosphorylation P» (ADP to ATP) without competing with P».

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  (P-L)/P is the OXPHOS P-L control efficiency. The biochemical coupling efficiency is independent of kinetic control by the phosphorylation system when expressed as the E-L coupling efficiency, (E-L)/E. (E-P)/E is the kinetic E-P control efficiency.

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1. Mitochondrial and cellular respiratory rates in coupling-control states

» Baseline state

Respiratory rate	Defining relations	Icon
OXPHOS capacity	P = P´-Rox		mt-preparations
ROUTINE respiration	R = R´-Rox		living cells
ET capacity	E = E´-Rox		» Level flow
			» Noncoupled respiration - Uncoupler
LEAK respiration	L = L´-Rox		» Static head
			» LEAK state with ATP
			» LEAK state with oligomycin
			» LEAK state without adenylates
Residual oxygen consumption Rox	L = L´-Rox

• Chance and Williams nomenclature: respiratory states

» State 1 —» State 2 —» State 3 —» State 4 —» State 5

2. Flux control ratios related to coupling in mt-preparations and living cells

» Flux control ratio

» Coupling-control ratio

» Coupling-control protocol

FCR	Definition	Icon
L/P coupling-control ratio	L/P		» Respiratory acceptor control ratio, RCR = P/L
L/R coupling-control ratio	L/R
L/E coupling-control ratio	L/E		» Uncoupling-control ratio, UCR = E/L (ambiguous)
P/E control ratio	P/E
R/E control ratio	R/E		» Uncoupling-control ratio, UCR = E/L
net P/E control ratio	(P-L)/E
net R/E control ratio	(R-L)/E

3. Net, excess, and reserve capacities of respiration

Respiratory net rate	Definition	Icon
P-L net OXPHOS capacity	P-L
R-L net ROUTINE capacity	R-L
E-L net ET capacity	E-L
E-P excess capacity	E-P
E-R reserve capacity	E-R

4. Flux control efficiencies related to coupling-control ratios

» Flux control efficiency j_Z-Y

» Background state

» Reference state

» Metabolic control variable

Coupling-control efficiency		Definition		Icon	Canonical term
P-L control efficiency	jP-L	= (P-L)/P	= 1-L/P		P-L OXPHOS-flux control efficiency
R-L control efficiency	jR-L	= (R-L)/R	= 1-L/R		R-L ROUTINE-flux control efficiency
E-L coupling efficiency	jE-L	= (E-L)/E	= 1-L/E		E-L ET-coupling efficiency » Biochemical coupling efficiency
E-P control efficiency	jE-P	= (E-P)/E	= 1-P/E		E-P ET-excess flux control efficiency
E-R control efficiency	jE-R	= (E-R)/E	= 1-R/E		E-R ET-reserve flux control efficiency

5. General

» Basal respiration

» Cell ergometry

» Dyscoupled respiration

» Dyscoupling

» Electron leak

» Electron-transfer-pathway state

» Hyphenation

» Oxidative phosphorylation

» Oxygen flow

» Oxygen flux

» Permeabilized cells

» Phosphorylation system

» Proton leak

» Proton slip

» Respiratory state

» Uncoupling

MitoPedia concepts: MiP concept, Respiratory control ratio, SUIT concept, Ergodynamics 

MitoPedia topics: Inhibitor, Substrate and metabolite, Uncoupler