Lecture 10- Enzyme Kinetics

Question 1

For competitive inhibitors, what happens to Vmax and Km?

Answer 1

There is a competition at the same binding active site. This means that Vmax stays the same, and Km increases (because affinity for the substrate decreases).

Question 2

For NONcompetitive inhibitors, what happens to Km and Vmax?

Answer 2

Vmax goes down, Km stays the the same.

Question 3

True or false: for uncompetitive inhibitors, you cannot bind to the substrate.

Answer 3

False. Binding can still happen, but enzyme cannot be processed.

Question 4

For both types of inhibitors, where will the graph shift to?

Answer 4

The graph will shift to the right.

Question 5

For steady state, what are we assuming?

Answer 5

The rate of binding of an enzyme to a substrate is equal to the rate of dissociation of an enzyme with its substrate.

Question 6

Vmax goes down, and Km stays the same. What type of inhibitor?

Answer 6

NONcompetitive inhibitor.

Question 7

Km increases, Vmax stays the same. What type of inhibitor?

Answer 7

Competitive inhibitor.

Question 8

What is uncompetitive inhibition? What is non competitive inhibition?

Answer 8

The inhibitor only binds to the enzyme when the enzyme is bound to the substrate; the inhibitor binds to a site other than an active site that causes a conformational change at the active site, which decreases activity.

Question 9

True or false: noncompetitive and uncompetitive inhibitors both decrease Vmax.

Answer 9

True.

Question 10

For uncompetitive inhibition, what happens to Vmax and Km? Why for each?

Answer 10

Both Km and Vmax decrease. Km decreases because it inhibits the disassociation of the ES complex into E+S. V max decreases because it inhibits the conversion of substrate into product (ES–>P+E is inhibited).

Question 11

How can competitive inhibition be overcome?

Answer 11

Adding higher concentrations of substrate.

Question 12

Km and Vmax both go down. What type of inhibition?

Answer 12

UNcompetitive inhibition.

Question 13

If allosteric changes in confirmation can be small/subtle, can they still have a big effect on catalysis?

Answer 13

Yes, movement of atoms

Within an active site by as little as one angstrom can have big effects on catalysis.

Question 14

What is allostery?

Answer 14

Binding of a molecule at a site other than the active site creates a conformational change at the active site.