Template:SUIT-037

Steps and respiratory states

Step	State	Pathway	Q-junction	Comment - Events (E) and Marks (M)
1D	ROX			1D ADP is added to stimulate consumption of endogenous fuel-substrates. Rox is the residual oxygen consumption in the ROX state, due to oxidative side reactions, estimated either after inhibition of CIII (e.g. antimycin A, myxothiazol), CIV (e.g. Cyanide) or in the absence of endogenous fuel-substrates. Rox is subtracted from oxygen flux as a baseline for all respiratory states, to obtain mitochondrial respiration.
2M.1				1D;2M.1 Low concentration of malate, typically 0.1 mM, does not saturate the N-pathway; but saturates the F-pathway. Malate kinetics in the presence of saturating [ADP] allows the evaluation of malate anaplerotic pathways.
2H2O				1D;2M.1;2H2O Respiratory stimulation of the FAO-pathway, F, by fatty acid, FA, in the presence of malate, M. Malate is a type N substrate (N), required for the F-pathway. The FA concentration has to be optimized to saturate the F-pathway, without inhibiting or uncoupling respiration.
3c				1D;2M.1;2H2O;2c OXPHOS capacity P (with saturating [ADP]), active OXPHOS state. Addition of cytochrome c yields a test for integrity of the mtOM (cytochrome c control efficiency). Stimulation by added cytochrome c would indicate an injury of the mtOM and limitation of respiration in the preceding state without added c due to loss of cytochrome c. Typically, cytochrome c is added immediately after the earliest ADP-activation step (OXPHOS capacity P with saturating [ADP]).
3M.2				1D;2M.1;2H2O;2c;3M.2 Malate kinetics in the presence of saturating [ADP] allows the evaluation of malate anaplerotic pathways. High concentration of malate, typically 2 mM, saturates the N-pathway. OXPHOS capacity P (with saturating [ADP]), active OXPHOS state.
3M.5				1D;2M.1;2H2O;2c;3M.2;3M.5 Malate kinetics in the presence of saturating [ADP] allows the evaluation of malate anaplerotic pathways. High concentration of malate, typically 2 mM, saturates the N-pathway. OXPHOS capacity P (with saturating [ADP]), active OXPHOS state.
3M1				1D;2M.1;2H2O;2c;3M.2;3M.5;3M1 Malate kinetics in the presence of saturating [ADP] allows the evaluation of malate anaplerotic pathways. High concentration of malate, typically 2 mM, saturates the N-pathway. OXPHOS capacity P (with saturating [ADP]), active OXPHOS state.
3M2				1D;2M.1;2H2O;2c;3M.2;3M.5;3M1;3M2 Malate kinetics in the presence of saturating [ADP] allows the evaluation of malate anaplerotic pathways. High concentration of malate, typically 2 mM, saturates the N-pathway. OXPHOS capacity P (with saturating [ADP]), active OXPHOS state.
4P	PMP	N	CI	1D;2M.1;2H2O;2c;3M.2;3M.5;3M1;3M2;4P NADH-linked substrates (type N-pathway to Q). OXPHOS capacity P (with saturating [ADP]), active OXPHOS state.
5G	PGMP	N	CI	1D;2M.1;2H2O;2c;3M.2;3M.5;3M1;3M2;4P;5G NADH-linked substrates (type N-pathway to Q). OXPHOS capacity P (with saturating [ADP]), active OXPHOS state.
6S10	PGMSP	NS	CI&II	1D;2M.1;2H2O;2c;3M.2;3M.5;3M1;3M2;4P;5G;6S10 Respiratory stimulation by simultaneous action of type N substrates & succinate, with convergent electron flow in the NS-pathway for reconstitution of TCA cycle function. OXPHOS capacity P (with saturating [ADP]), active OXPHOS state.
6S50	PGMSP	NS	CI&II	1D;2M.1;2H2O;2c;3M.2;3M.5;3M1;3M2;4P;5G;6S10;6S50 Respiratory stimulation by simultaneous action of type N substrates & succinate, with convergent electron flow in the NS-pathway for reconstitution of TCA cycle function. OXPHOS capacity P (with saturating [ADP]), active OXPHOS state.
7Gp	PGMSGpP	NSGp	CI&II&GpDH	1D;2M.1;2H2O;2c;3M.2;3M.5;3M1;3M2;4P;5G;6S10;6S50;7Gp Respiratory stimulation by simultaneous action of type N substrates (N), succinate (S), and glycerophosphate with convergent electron flow in the NSGp-pathway to the Q-junction. OXPHOS capacity P (with saturating [ADP]), active OXPHOS state.
8U	PGMSGpE	NSGp	CI&II&GpDH	1D;2M.1;2H2O;2c;3M.2;3M.5;3M1;3M2;4P;5G;6S10;6S50;7Gp;8U Respiratory stimulation by simultaneous action of type N substrates (N), succinate (S), and glycerophosphate with convergent electron flow in the NSGp-pathway to the Q-junction. 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.
9Rot	SGpE	SGp	CII&GpDH	1D;2M.1;2H2O;2c;3M.2;3M.5;3M1;3M2;4P;5G;6S10;6S50;7Gp;8U;9Rot Respiratory stimulation by action of succinate and glycerophosphate, Gp, with convergent electron flow in the SGp-pathway (CII&GpDH-linked pathway to the Q-junction). Noncoupled electron transfer state, ET state, with ET capacity E.
10Ama	ROX			1D;2M.1;2H2O;2c;3M.2;3M.5;3M1;3M2;4P;5G;6S10;6S50;7Gp;8U;9Rot;10Ama 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).

Bioblast links: SUIT protocols - >>>>>>> - Click on [Expand] or [Collapse] - >>>>>>>

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