Enzymes 2

Question 1

Michalis Menten Plot

Answer 1

Just be aware of vague shape so you can image/identify it

Question 2

Pre-Steady State

Answer 2

The study of the few microseconds after the moment an enzyme is mixed with substrate and no product or intermediates have been formed where product formation is unsteady

Question 3

Steady State

Answer 3

When the rate of formation and breakdown of the intermediate are equal

Question 4

V₀

Answer 4

Initial Rate of reaction

Question 5

K_m

Answer 5

Michaelis Constant - The Concentration of the substrate at half V_max

Question 6

V_max

Answer 6

Speed of enzyme reaction at infinite substrate concentration (Maximum enzyme rate)

Question 7

How to increase Vmax

Answer 7

Increase the amount of enzyme

Question 8

Interpret K_m

Answer 8

Low - High Substrate Affinity

High - Low Substrate Affinity

**THINK LOGICALLY - IF AN ENZYME HAD HIGH SUBSTRATE AFFINITY, ITS KM WOULD BE LOW BECAUSE IT WOULD TAKE NOT MUCH SUBSTRATE FOR HALF Vmax TO BE REACHED

Question 9

Describe the order of enzyme reactions relative to a change substrate concentrations when substrate concentration is high vs when it is low

Answer 9

When [substrate] high, it is a 0 order reaction

When low it is a first order reaction

Question 10

S_0.5

Answer 10

Equivalent of K_m for multisubunit enzymes as they do not follow the michaelis menton equation/hyperbolic shape

Question 11

Isozymes

Answer 11

Different forms of an enzyme that catalyse the same thing - they often differ in their Km values based on the role of the enzyme

**Think of function, hexokinase has low Km that will permit even a little glucose to enter glycolysis, while glucokinase is involved in storage so has a higher Km (worse substrate affinity)

Question 12

Effects of a competitive inhibitor on Vmax

Answer 12

No Effect

Question 13

Effects of a competitive inhibitor on Km

Answer 13

Km increases as enzyme affinity is reduced

Question 14

Effect of a non-competitive inhibitor on Vmax

Answer 14

Lowers Vmax as it lowers the concentration of the enzyme

Question 15

Effect of a non-competitive inhibitor on Km

Answer 15

Not affected as the functional enzymes do not have their affinity affected

Question 16

Uncompetitive Inhibition

Answer 16

When an inhibitor binds to an enzyme-substrate complex and prevents catalysis

Question 17

Dead-end complex

Answer 17

[ESI] Complex made by an uncompetitive inhibitor

**E = Enzyme, S = Substrate, I = Inhibitor

Question 18

When can a substrate of an enzyme act as its inhibitor

Answer 18

At very high substrate concentrations

Question 19

Describe a lineweaver burke plot

Answer 19

Vague awareness

Just know Vmax and Km

Question 20

Why might a linweaver burke plot have a hockey stick shape

Answer 20

Due to the substrate acting as an uncompetitive inhibitor by binding to a second non-catalytic site

Question 21

Why is non-competitive inhibition irreversible

Answer 21

They form covalent bonds with the enzyme and inhibit its function

Question 22

Examples of two irreversible inhibitors

Answer 22

• Lead
• Carbon Monoxide
  
  • Penicillin

Question 23

Suicide Inhibitor

Answer 23

Inhibitor that only becomes such when an enzyme acts on it via its active site

Used in drug design

Question 24

Describe a lineweaver burke plot

Answer 24

Vague awareness

Just know Vmax and Km