P-L net OXPHOS capacity

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P-L net OXPHOS capacity

Description

The P-L net OXPHOS capacity is the OXPHOS capacity corrected for LEAK respiration. P-L is the scope for ADP stimulation, the respiratory capacity potentially available for phosphorylation of ADP to ATP. Oxygen consumption in the OXPHOS state, therefore, is partitioned into P-L, strictly coupled to phosphorylation P», and nonphosphorylating LEAK respiration, L_P, compensating for proton leaks, slip and cation cycling: P = P-L+L_P. It is frequently assumed that LEAK respiration L as measured in the LEAK state, overestimates the LEAK component of respiration, L_P, as measured in the OXPHOS state, particularly if the protonmotive force is not adjusted to equivalent levels in L and L_P. However, if the LEAK component increases with enzyme turnover during P, the low enzyme turnover during L may counteract the effect of the higher pmF.

Abbreviation: P-L

Reference: Gnaiger 2020 BEC MitoPathways

Communicated by Gnaiger E (2014-08-09) last update 2020-11-11

Keywords

Expand Bioblast links to P-L net OXPHOS capacity

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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.
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».
(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.

Bioblast links: Coupling control - >>>>>>> - Click on [Expand] or [Collapse] - >>>>>>>

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

» Baseline state

Respiratory rate	Defining relations
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
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		Canonical term
P-L control efficiency	j_P-L	= (P-L)/P	= 1-L/P	P-L OXPHOS-flux control efficiency
R-L control efficiency	j_R-L	= (R-L)/R	= 1-L/R	R-L ROUTINE-flux control efficiency
E-L coupling efficiency	j_E-L	= (E-L)/E	= 1-L/E	E-L ET-coupling efficiency » Biochemical coupling efficiency
E-P control efficiency	j_E-P	= (E-P)/E	= 1-P/E	E-P ET-excess flux control efficiency
E-R control efficiency	j_E-R	= (E-R)/E	= 1-R/E	E-R ET-reserve flux control efficiency