Description
Abbreviation: RET
Reference: A - SUIT-026
SUIT number: D064_1S;2Rot;3D;4Ama
O2k-Application: AmR
- MitoPedia: SUIT - Protocol for the evaluation of ROS production by RET in mtprep
- SUIT protocol pattern: 1S;2Rot;3D;4Ama
SUIT-026 AmR mt D064 has been designed to study the RET-initiated ROS production in mitochondrial preparations (isolated mitochondria and tissue homogenate and permeabilized cells which are already permeabilized when they are added to the chamber). The protocol is focused on LEAK state for the S-pathway to provide the conditions of high membrane potential and redox power in the Q-junction. Under these conditions, in several samples has been described that a reverse flow of the electrons into the membrane arm and the quinone binding site of the Complex I occurs, promoting the production of ROS. The addition of rotenone provides excellent control to this mechanism because this compound blocks the point on which the electrons leak from the Complex I leading to decreased ROS production. If rotenone would have been added before S titration, it had inhibited the RET. The titration of ADP at saturating concentrations to reach OXPHOS allows us to harmonize this protocol with SUIT-006 O2 mt D022 for quality control and a full assessment of the coupling control. Addition of Ama leads to increased ROS production via inhibition of Complex III at the Qi site.
Communicated by Komlodi T, Iglesias-Gonzalez J and Gnaiger E (last update 2019-06-26)
Steps and respiratory states
Step | State | Pathway | Q-junction | Comment - Events (E) and Marks (M) |
---|---|---|---|---|
0DTPA |
| |||
0SOD |
| |||
0HRP |
| |||
0AmR |
|
Step | State | Pathway | Q-junction | Comment - Events (E) and Marks (M) |
---|---|---|---|---|
1S | SL(n) | S | CII | 1S
|
2Rot | SL(n) | S | CII | 1S;2Rot
|
3D | SP | S | CII | 1S;2Rot;3D
|
4Ama | ROX | 1S;2Rot;3D;4Ama
|
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- Coupling control
- Pathway control
- Β» Electron transfer pathway
- Β» Fatty acid oxidation pathway control state, F
- Β» NADH electron transfer-pathway state, N
- Β» Succinate pathway control state, S
- Β» NS-pathway control state, NS
- Β» Glycerophosphate pathway control state, Gp
- Β» Complex IV single step, CIV
- Β» Anaplerotic pathway control state
- Pathway control
- Main fuel substrates
- Β» Glutamate, G
- Β» Glycerophosphate, Gp
- Β» Malate, M
- Β» Octanoylcarnitine, Oct
- Β» Pyruvate, P
- Β» Succinate, S
- Main fuel substrates
- Glossary
Strengths and limitations
- The conditions on which RET is observable in isolated mitochondria are not physiological but it has been suggested that corresponds to some pathological states.
- + This protocol must be run in parallel with SUIT-026 O2 mt D063 to have a respiratory control, since many fluorescence dyes can inhibit components of the ET system, thus affecting the respiration.
- + Short duration of the experiment.
- + Rotenone provides an excellent control step for RET.
- - This protocol does not provide information about all the coupling control states (LEAK, OXPHOS and ET). However, it is possible to create a DLPU by additing an Event&Mark for the uncoupler titration (4U) after ADP (3D) to obtain ET-state.
- - The addition of cytochrome c cannot be done in this SUIT protocol (SUIT-026 O2 mt D063 must be run in parallel to assess the mt outer membrane integrity as a quality control of the sample).
- - Measurements with Amplex UltraRed assay cannot be carried out with liver homogenate.
Compare SUIT protocols
- SUIT-026 O2 mt D063: Respiratory control protocol.
- SUIT-006 O2 mt D022: CCP with mtprep for S-pathway.
References
MitoPedia concepts: SUIT protocol, SUIT A, Find
MitoPedia methods:
Fluorometry