Template:SUIT-006 Q mt D071

Steps and respiratory states

Step	State	Pathway	Q-junction	Comment - Events (E) and Marks (M)
1Q2	REN			1Q2 To detect the redox state of the Q-pool a mimetic coenzyme Q2 is applied in suspension, which reacts both with the detecting electrode and the biological sites (CI, CII and CIII). Respiration in the REN state is due to the presence of residual endogenous substrates in the sample preparation. In the absence of endogenous substrates, this step can be used for calibration of fully oxidized Q.
1Rot	ROX			1Rot Rotenone is required to detect the fully oxidized Q-pool in the presence of isolated mitochondria (or permeabilized cells) and coenzyme Q2. Rotenone can inhibit the respiration supported by endogenous substrates that remained after the isolation procedure.
1S	SL	S	CII	1Q2;1Rot;1S Succinate, S ( type S-pathway to Q). Non-phosphorylating resting state (LEAK state); LEAK respiration L(n) in the absence of ADP, ATP, AMP (no adenylates).
2D	SP	S	CII	1Q2;1Rot;1S;2D Succinate, S ( type S-pathway to Q). OXPHOS capacity P (with saturating [ADP]), active OXPHOS state.
(3Omy)	SL(Omy)	S	CII	1Q2;1Rot;1S;2D;(3Omy) Omy addition is skipped in SUIT-006 O2 mt D022 Succinate, S ( type S-pathway to Q). Non-phosphorylating resting state (LEAK state); LEAK-respiration, L(Omy), after blocking the ATP synthase with oligomycin.
4U	SE	S	CII	1Q2;1Rot;1S;2D;(3Omy);4U Succinate, S ( type S-pathway to Q). Uncoupler titration (avoiding inhibition by high uncoupler concentrations) to obtain electron transfer (ET) capacity E (noncoupled ET-state). Test for limitation of OXPHOS capacity P by the phosphorylation system (ANT, ATP synthase, phosphate transporter) relative to ET capacity E in mt-preparations: E-P control efficiency and E-L coupling efficiency. In living cells: E-R control efficiency and E-L coupling efficiency.
5Anox		S	CII	1Q2;1Rot;1S;2D;(3Omy);4U;5Anox Anoxia is a crucial step to detect the fully reduced Q-junction in the presence of coenzyme Q2 after the biological sample has consumed the O2 in the O2k-chamber for calculation of the Q redox state.
6Ama				1Q2;1Rot;1S;2D;(3Omy);4U;5Anox;6Ama Rox is the residual oxygen consumption in the ROX state, due to oxidative side reactions, estimated after addition of antimycin A (inhibitor of CIII). Rox is subtracted from oxygen flux as a baseline for all respiratory states, to obtain mitochondrial respiration (mt). Since the previous step was anoxia, it is essential to reoxygenate the chamber before or after antimycin A titration to be able to measure Rox.

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Coupling control

» Coupling control state

» ET capacity

» OXPHOS capacity

» LEAK respiration

Pathway control

» Electron transfer pathway

» Fatty acid oxidation pathway control state, F

» NADH electron transfer-pathway state, N

» Succinate pathway control state, S

» NS-pathway control state, NS

» Glycerophosphate pathway control state, Gp

» Complex IV single step, CIV

» Anaplerotic pathway control state

Main fuel substrates

» Glutamate, G

» Glycerophosphate, Gp

» Malate, M

» Octanoylcarnitine, Oct

» Pyruvate, P

» Succinate, S

Glossary

» List of SUIT states

» SUIT concept