P-L net OXPHOS capacity

high-resolution terminology - matching measurements at high-resolution

P-L net OXPHOS capacity

Description

The free OXPHOS capacity, ≈P, is the OXPHOS capacity corrected for LEAK respiration, ≈P = P-L. ≈P 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 the free OXPHOS capacity, ≈P, strictly coupled to phosphorylation, ~P, and nonphosphorylating LEAK respiration, L_P, compensating for proton leaks, slip and cation cycling: P = ≈P+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 Δp_mt.

Abbreviation: ≈P

Reference: Gnaiger 2014 MitoPathways

MitoPedia concepts: Respiratory state 

The Blue Book 2014: Fig. 2.4.

Coupling control states for ≈P

» Respiratory state

• Reference state, Z_X: OXPHOS capacity, P = P´-ROX
• Background state, Y_X: LEAK respiration, L = L´-ROX
• Metabolic control variable, X=Z_X-Y_X: Scope of ADP stimulation, free OXPHOS capacity, ≈P = P-L

Flux control factor

» Flux control factor, FCF

• Coupling control factor, 1-Y_X/Z_X: P-L coupling control factor, OXPHOS coupling efficiency: j_≈P = ≈P/P =(P-L)/P = 1-L/P

Compare

Free ETS capacity, ≈E = E-L

netOXPHOS control ratio, ≈P/E control ratio: ≈P/E = (P-L)/E

ETS coupling efficiency, E-L control factor: j_≈E = ≈E/E = (E-L)/E = 1-L/E

• Intact cells: Free ROUTINE activity, ≈R = R-L