ATP Synthase and ATP Yields

What is the proton motive force?

A combination of \[H+\] concentration gradient and electrical potential difference across IMS and Matrix

What does the F0 stalk of ATP Synthase do?

Acts as the motor by taking H+ via a subunit and sending it through the c ring

What AA exists on the C-ring that attaches protons to it?

Asp59

How many c subunits are in the c ring?

10

What are the subunits of the F1 portion of ATP synthase?

hexamer of α and β subunits, with γ subunit in the middle

What are the possible confirmations of the α and β subunits? Which way is the γ subunit turning in normal ATP synthesis?

Clockwise movement (O→L→T)

O: ADP + Pi bond (ATP released)

L: ADP + Pi locked

T: ATP formed

How much ATP does one full turn of ATP synthase form?

3 ATP

Which UCLA professor found the rotational ATP synthase model?

Paul Boyer

Do you know what the reaction coordinate diagram of ATP Synthase looks like?

This

How does ADP get to the mitrochondrial matrix?

Adenine Nucleotide Translocase transport 1 ATP into IMS and 1 ADP into matrix at the same time

How does inorganic Phosphate (Pi) transported into the matrix?

Phosphate Translocase Symporter transports 1 Pi in and 1 H+ out. It can also symport 3H+ for 1 ADP.

What 3 compounds form the ATP-synthasome complex?

ATP synthase, Adenine nucleotide translocase, and phosphate translocase

The ETC and TCA are said to be _____ coupled

Obligately

What does adding ADP + Pi do to ATP synthesis

Nothing

What does adding Succinate do to ATP synthesis?

ETC activate, increasing ATP synthesis

What does adding CN- do to ATP Synthesis?

ETC blocked, ATP synthe halts

What uncouplers can uncouple ETC from ATP Synthesis?

2,4 DNP and FCCP

What do uncouplers do?

Move H+ without the need for e-’s; destroys proton gradient

What do malate and aspartate do in the malate aspartate shuttle?

Transfer e-’s

How does NADH get into the mitochondrial matrix from the IMS?

The Malate-Aspartate shuttle and the G3P Shuttle

What does glutarate and a-ketoglutarate do in the malate-aspartate shuttle?

Amino group donors/acceptors

How much ATP does the Malate-Aspartate shuttle yield compared to the G3P Shuttle?

2\.5 ATP compared to 1.5 ATP

Does the G3P shuttle need transporters?

No

Why does the G3P Shuttle produce less ATP than the Malate-Aspartate Shuttle?

It bypasses Complex I (misses out on proton pumping here)

What happens if no O2 is present?

Proton motive force collapses, stopping or reversing ATP synthase

If ATP Synthased is reversed (clockwise), what happens to ATP?

It is depleted by ATP Synthase

What genes are activated in hypoxic conditions that help with hypoxia? What do they do?

IF1 → binds ATP synthase dimers and stops reversal

HIF1 → Removes reactive Oxygen species by stopping PDH and replaced Subunit IV’s COX4-1 with COX4-2, which is better suited for low O2 concentrations

What is the total ATP yield?

30-32 ATP depending on which shuttle is used to bring NADH to ETC