Class 3: Ox Phos 2 Flashcards
Chemiosmotic hypothesis
Atp synthesis coupled to proton gradient
Generates pH gradient and membrane potential.
Proof of ATP synthase
Bacteriorhodopsin in synaptic vesicle
The stick and proton channel for ATP synthase
Embedded in the membrane
F0
The ball and catalytic domain of ATP synthase:
F1
Complex V
ATP synthase
Made of 5 types of polypeptide chains w/ different stochiometries:
Alpha3, Beta3, gamma, delta, and epsilon
F1
Alpha ad beta are arranged in
Hexameric ring
Only polypeptide in F1 that is catalytically active
Beta
Stalk of F1 is made up of:
Gamma and epsilon proteins
Long helical coil that extends into the center of the alpha3 and beta 3 hexamer
Gamma subunit
A proton channel made of 8-14 c subunits embedded in membrane
F0
F0 and F1 connected in 2 ways:
- Central gamma and epsilon stalk
2. Exterior column- 1 a su, 2 b su, and delta su
Allows the proton gradient to be in close proximity to the ATP synthase
Cristae
molecules asso. W/ each other to form dimers then oligomers
ATP synthase
What is the role of the proton gradient in Ox phos
Release the ATP from the synthase
Which subunits of F1 are catalytically active?
Beta
3 beta subunits conformational change alters function in
Active site of ATP synthase
3 steps of ATP synthesis:
- Binding of ADP+Pi (L)
- ATP synthesis (T)
- Release of ATP (O)
Rotation of which su switches the forms of ATP synthesis
Gamma
ATP synthesis conformations change in what order
LTOLTO
What direction does ATP synthase conformational rotation?
clockwise
Which su expressed w/ poly His tag
Alpha and beta
Made up of 2 a helices that span membrane.
An asp acid residue lies in the center of the membrane
Has 2 half channels
Proton doesnt completely pass
C subunit of ATP synthase
Each 360 degree rotation of gamma su powered by 3 protons generates how much ATP?
3 ATP
ATP and ADP are not permeable across mito membrane. Needs a carrier:
ATP-ADP translocase
The flow of ATP and ADP are coupled= ADP enters only if ATP leaves
What regulates cellular respiration?
Levels of ATP
When do electrons flow through ETC?
When ADP phosphorylated to ATP
Regulation of ADP levels =
Respiratory control
More ADP added=
More O2 consumed
Inhibits hydrolytic activity of ATP synthase
Prevents ATP breakdown in ischemia or O2 deprivation.
Upregulated in CA- facilitates the switch from aerobic to anaerobic (warburg effect)
Inhibitory factor I
Some organisms can uncouple ox phos from ATP synthesis to generate heat happens in brown adipose tissue
Transfer protons from cytoplasm to matrix
What protein is used in inner mito. Membrane?
UCP 1 (thermogenin)
Also, UCP 2 and UCP 3
Helps in energy homeostasis
Action of UCP 1?
Energy is converted to heat instead of ATP
Inhibition of ATP synthase: inhibits influx of protons into ATP synthase by binding to c su
Oligomyocin
Uncoupling E- transport from ATP synthesis - dissipates the H+ gradient
2,4-dinitrophenol
Inhibiton of ATP export and inhibits ATP-ADP translocase
Atractyloside and bongkrekic acid
Inhibits Complex 1
Rotenone and amytal
Blocks complex 3
Antimycin A
Blocks complex 4
Cyanide, N3, and CO
