Enzyme Regulation II: ATCase

Question 1

What does ATCase stand for?

Answer 1

Aspartate Transcarbamoylase.

Question 2

What type of inhibition is Astec regulation of metabolic pathways using ATCase?

Answer 2

Feedback inhibition.

Question 3

Why is it good that ATP stimulates ATCase?
Fill in the blanks.

Answer 3

It’s one of the ways to balance the ATP and CTP concentrations in the cell.
We want to keep purines and pyrimidines in equal concentrations!

Question 4

What should we take away from this graph?

Answer 4

Question 5

Understanding ATCase kinetics, fill in the blanks.

Answer 5

Question 6

What is the right picture representing?

Answer 6

That CTP inhibits its own production, while ATP stimulates CTP’s production. Balancing both products outputs to be equal!

Question 7

What is the symmetry of ATCase? Describe the structure.

Answer 7

D3 point symmetry.

Question 8

Fill in the blanks.

Answer 8

Question 9

For ATCase is the T-state or R-state more active?

Answer 9

R State

Question 10

1. What is the name of the ATCase inhibitor we learned about?
2. What type of inhibitor is it?
3. It looks like a reaction intermediate but isn’t. What is it?

Answer 10

1. PALA
2. Potent competitive inhibitor.
3. bisubstrate analog

Question 11

Based on the image, you see that PALA makes ATCase conform to the R state. It is an inhibitor. How does this work?

Answer 11