Enzyme Kinetics Flashcards

1
Q

What are kinetics?

A

The rate of a reaction

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2
Q

Will enzyme activity increase when more substrate is added?

A

Yes, until it reaches saturation

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3
Q

What is Vmax?

A

The reaction rate at saturation, when every active site is filled

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4
Q

What type of curve will an enzyme with cooperativity have?

A

Sigmoidal

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5
Q

What is Km?

A

The Michaelis constant. Indicates affinity of the enzyme

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6
Q

What is the relationship between Km and substrate affinity?

A

High Km = low affinity

Low Km = high affinity

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7
Q

Why is it hard to determine Vmax from an MM graph?

A

Asymptotic relationship, not linear

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8
Q

What is the Y-intercept in an LB graph?

A

1/Vmax

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9
Q

What is the X-intercept in an LB graph?

A

-1/Km

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10
Q

What is the slope in an LB graph?

A

Km/Vmax

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11
Q

Where does a competitive inhibitor bind?

A

Active site. It looks very similar to the substrate and actively competes with it for the active site

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12
Q

How does a competitive inhibitor affect Vmax and Km?

A

Vmax doesn’t change, but Km will increase

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13
Q

What happens to enzyme activity when an allosteric modifier binds?

A

Activity can either increase or decrease, depends on what the molecule is

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14
Q

Where does a non-competitive inhibitor bind?

A

Allosteric site. It changes the conformation of the active site so the substrate will bind but can’t react

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15
Q

How does a non-competitive inhibitor affect Vmax and Km?

A

Vmax changes, but Km doesn’t

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16
Q

What is feedback inhibition?

A

Buildup of a downstream product will slow down upstream reactions

17
Q

How do we predict which metabolic pathway a substrate will go into?

A

Calculate Vmax and Km

18
Q

What determines if pyruvate will enter fermentation or CAC?

A

Presence of oxygen

19
Q

What are allosteric activators of glycolysis?

A

CoA, AMP, ADP, NAD+

20
Q

What are allosteric inhibitors of glycolysis?

A

Acetyl-CoA, Citrate, ATP, NADH

21
Q

What are the 3 metabolic pathways that oxaloacetate can go into?

A

CAC, aspartate biosynthesis, gluconeogenesis

22
Q

What enzyme uses oxaloacetate in the CAC?

A

Citrate synthase

23
Q

What are the allosteric inhibitors of the CAC?

A

ATP, acetyl-CoA, succinyl-CoA, NADH

24
Q

What enzyme uses oxaloacetate in gluconeogenesis?

A

Carboxykinase

25
What is the allosteric inhibitor of gluconeogenesis?
DPNH
26
What enzyme uses oxaloacetate in aspartate biosynthesis?
Aspartate amino transferase
27
What determines if oxaloacetate will go into the CAC, gluconeogenesis, or Asp biosynthesis?
Km, which will change depending on what the cell needs