Template:SUIT-001

Steps and respiratory states

Step	State	Pathway	Q-junction	Comment - Events (E) and Marks (M)
1PM	PML(n)	N	CI	1PM NADH-linked substrates (type N-pathway to Q). Non-phosphorylating resting state (LEAK state); LEAK-respiration, L(n), in the absence of ADP, ATP, AMP (no adenylates).
2D	PMP	N	CI	1PM;2D NADH-linked substrates (type N-pathway to Q). OXPHOS capacity, P (with saturating [ADP]), active OXPHOS state.
2c	PMcP	N	CI	1PM;2D;2c NADH-linked substrates (type N-pathway to Q). OXPHOS capacity, P (with saturating [ADP]), active OXPHOS state. Addition of cytochrome c yields a test for integrity of the mtOM. 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 (P, OXPHOS-capacity with saturating [ADP]).
3U	PME	N	CI	1PM;2D;3U NADH-linked substrates (type N-pathway to Q). Uncoupler titration (avoiding inhibition by high uncoupler concentrations) to obtain electron transfer (ET) capacity (noncoupled ET-state), as a test for limitation of OXPHOS-capacity by the phosphorylation system (ANT, ATP synthase, phosphate transporter) relative to ET-capacity, E.
4G	PGME	N	CI	1PM;2D;3U;4G NADH-linked substrates (type N-pathway to Q). Noncoupled electron transfer state, ET-state, with ET-capacity, E.
5S	PGMSE	NS	CI&II	1PM;2D;3U;4G;5S Respiratory stimulation by simultaneous action of type N substrates & succinate, with convergent electron flow in the NS-pathway for reconstitution of TCA cycle function. Noncoupled electron transfer state, ET-state, with ET-capacity, E.
6Oct	OctPGMSE	FNS	FAO&CI&II	1PM;2D;3U;4G;5S;6Oct Respiratory stimulation by simultaneous action of fatty acid (F), type N substrates (N), and succinate (S), with convergent electron flow in the FNS-pathway for reconstitution of TCA cycle function and additive or inhibitory effect of F. Noncoupled electron transfer state, ET-state, with ET-capacity, E.
7Rot	SE	S	CII	1PM;2D;3U;4G;5S;6Oct;7Rot Succinate pathway control state (S-pathway) after inhibiting CI with rotenone, which also inhibits the F-pathway if fatty acids are present. Noncoupled electron transfer state, ET-state, with ET-capacity, E.
8Gp	SGpE	SGp	CII&GpDH	1PM;2D;3U;4G;5S;6Oct;7Rot;8Gp 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.
9Ama	ROX			1PM;2D;3U;4G;5S;6Oct;7Rot;8Gp;9Ama 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).

Step	Respiratory state	Pathway control	ET-Complex entry into Q-junction	Comment
## AsTm	AsTmE	CIV	CIV
## Azd	ROX

» Selected keywords in SUIT protocols

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