Ox Phos - Inhibitors of Respiratory Chain Complexes Flashcards
Which inhibitor targets complex I?
Rotenone
- specific inhibitor
Which inhibitor targets cytochrome bc1?
antimycin A
What does cyanide inhibit?
CN- mimics oxygen and stops O2 form binding to complex IV
What does malonate inhibit?
mimics succinate, is a competitive inhibitor for complex II
What experiment can be done to test the inhibition of the respiratory chain complexes?
- measure [O2] across time
1. start off with air-saturated Pi buffer
2. add mitochondria + uncoupler - O2 levels will dip a bit but there is still no source of e-
3. add pyruvate - this provides the e- so the [O2] decreases
4. adding rotenone - inhibits complex 1 so no further repiration
- [O2] stay the same
5. adding succinte - If we add succinate, O2 decreases, showing that complex 1 must be upstream than complex II. Feeding e in
6. adding malonate - inhibits/ blocks complex II
Which two gradients generated by the respiratory chain operate together to form the proton motor force Δp?
pH gradient
membrane potential - electrical gradient
What is the proton motor force equation Δp?
Δp = Δelectrical gradient - 0.06ΔpH
What is the structure of the H+ ATPase?
- large and complex
- F1 part and F0 part
- F0 is a proton motor in the membrane
- F1 has a long bent coil that rotates
What is the need for the ATPase?
Channel that allows proton back through into the matrix from the intermembrane space
- As proton comes back through - releases energy
- Energy uses ADP + Pi ——> ATP
How many H+ are transported through the F0 per ATP made?
3-4 (3.3)
How does phosphate, ATP and ADP cross the inner mitochondrial membrane?
Through the AdN transporter and the Phosphate Translocase
What is the AdN Transporter?
- antiporter
- compulsory exchange
- 1ADP goes into matrix 1ATP goes out into the inner membrane space
- ADP & ATP differ by 1- charge
- net negative outside
- driven by Δelectrical gradient
What is the Phosphate Translocase?
- symporter
- compulsory co-transport
- 1 phosphate (Pi-) and 1 proton (H+) goes in
- net is neutral
Where does atractyloside inhibit?
disrupts the mitochondria and gives inverted mitochondria,
- ATP synthase on the outside
What do uncoupling agents do?
- uncouple the ETC from ATP Synthase
- Sit in the membrane and picks up proton and delivers proton to other side
- Back onto matrix side
- Kinetically much faster than ATP synthase so protons go through this
