Lecture 13 - Enzymes III Flashcards Preview

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Flashcards in Lecture 13 - Enzymes III Deck (14):
1

ATCase acts as a(n) ______ of pyrimidine synthesis depending on CTP vs ATP binding.

Regulator

2

ATCase regulatory and catalytic subunits are bound to each other by ____

a zinc domain

3

CTP works to "lock" ATCase into the ____-state (doesn't bind substrate)

tense or "T-state"

4

When in the T-state, ATCase does or does not produce pyrimidines

does not

5

This class of enzyme adds inorganic phosphates to proteins

Kinases

6

This class of enzyme removes inorganic phosphates from proteins

phosphatase

7

Why is AMP a potent regulator of enzymes (specifically kinases)?

AMP is produced when Pi is removed from ATP (as a result of cellular E* stores being low). AMP activates kinases to produce more ATP by phosphorylation

8

What is the name of an inactive protein that is awaiting cleavage to become active?

a "zymogen"

9

Pepsinogen is one of the few protease zymogens found in the _____

stomach

10

Two types of allosteric control in enzymes

Inhibition and activation

11

All substrates must bind to the enzyme prior to product release in this type of bisubstrate reactions

What is "sequential reactions?"

12

One substrate binds, product is released, then another substrate binds to enzyme in this type of bisubstrate reaction.

Double-displacement reaction

13

What is the (+) allosteric regulator for ATCase? Why is this particular molecule an ATCase inhibitor?

ATP; ATP is the byproduct of purine synthesis-therefore, increased ATP signifies that the "competing" purine pathway is more active. Since purines bind pyrimidines, it makes sense to increase pyrimidine synthesis!!!

14

Acts to dephosphorylate adenyl cyclase when intracellular calcium is high

PP2B (aka "calcineurin")