Enzymes

Question 1

ΔG = ?, ΔG<0 vs. ΔG>0

Answer 1

ΔG = ΔH - TΔS (difference of energy between the reactants and products)
ΔG<0 spontaneous
ΔG>0 non-spontaneous

Question 2

large Ea vs. small Ea

Answer 2

large = slow reaction
small = fast reaction

Question 3

What is activation energy?

Answer 3

the energy required to produce the transition state

Question 4

What is the purpose of catalysts?

Answer 4

1. lower Ea
2. stabilizes T.S.

Question 5

Name 2 ways that enzymes are regulated and the results that occur from regulation.

Answer 5

1. phosphorylation of enzyme
2. allosteric modulation
   Result of regulation:
   -negative feedback or positive feedback, product made inhibits or promotes enzyme activity, respectively

Question 6

Define Vmax, Km and their relationship

Answer 6

Vmax: the max rate of product formation
Km: affinity the enzyme has for the substrate
-Large Km value: weak affinity
-small Km value: strong affinity
Km is the substrate concentration required to reach 1/2 of Vmax.

Question 7

True or False? Vmax depends on substrate and enzyme concentration.

Answer 7

FALSE!!!!!
it only depends on enzyme concentration :0

Question 8

State the changes to Km and Vmax during competitive, noncompetitive, and uncompetitive inhibition

Answer 8

Competitive: binds at active site
-Km increases, Vmax stays the same
Noncompetitive: binds to allosteric site of enzyme alone
-Km stays the same, Vmax decreases
Uncompetitive: binds to allosteric site of enzyme-substrate complex
-Km decreases, Vmax decreases

Question 9

Know the linweaver burk plots, shape, slopes…
-getting closer to the origin means Km or Vmax has increased
-x-intercept: Km
-y-intercept: Vmax

Question 10

Should you use a V vs. S plot or lineweaver burk plot when estimating reaction kinetics? Why?

Answer 10

Lineweaver burk plots because they are more accurate, linear graph vs hyperbolic graph

Question 11

what is cooperative binding, what is the prerequisite for an enzyme to be able to cooperatively bind, and what does a graph of an enzyme that undergoes cooperative binding look like?

Answer 11

cooperative binding is when the binding of some substrate facilitates the binding of more substrate until saturation is reached, the enzyme must be made up of more than one subunit, the graph is a sigmoidal curve