Lecture 13 - Enzymes III Flashcards

1
Q

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

A

Regulator

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2
Q

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

A

a zinc domain

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3
Q

CTP works to “lock” ATCase into the ____-state (doesn’t bind substrate)

A

tense or “T-state”

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4
Q

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

A

does not

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5
Q

This class of enzyme adds inorganic phosphates to proteins

A

Kinases

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6
Q

This class of enzyme removes inorganic phosphates from proteins

A

phosphatase

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7
Q

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

A

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

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8
Q

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

A

a “zymogen”

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9
Q

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

A

stomach

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10
Q

Two types of allosteric control in enzymes

A

Inhibition and activation

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11
Q

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

A

What is “sequential reactions?”

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12
Q

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

A

Double-displacement reaction

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13
Q

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

A

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!!!

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14
Q

Acts to dephosphorylate adenyl cyclase when intracellular calcium is high

A

PP2B (aka “calcineurin”)

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