Kinetics (reversible binding reactions)

Question 1

How do you calculate the rate of formation of PL in a reversible binding reaction?

Answer 1

rate = K1[P][L]

Question 2

How do you calculate the rate of loss of PL in a reversible binding reaction?

Answer 2

rate = K-1[PL]

Question 3

At equilibrium, describe the rates of reactions in a reversible binding reaction

Answer 3

-rates are balances
-K1[P][L] = K-1[PL}

Question 4

What is Kd?

Answer 4

-equilibrium constant for dissociation reaction
-equation must be written this way round
-Kd = ([P][L]) / [PL] = K-1 / K1

Question 5

How can tighter binding ligands be achieved?

Answer 5

-by ligand going into binding site faster
-by ligand leaving binding site slower

Question 6

What does a lower Kd mean?

Answer 6

Stronger ligand binding
-Kd = Koff / Kon

Question 7

How is a lower Kd achieved?

Answer 7

-decreasing Koff
-increasing Kon

Question 8

At equilibrium, what is Kd equal to?

Answer 8

Kd = ([P][L]) / [PL]

Question 9

How do you calculate the total P and L concentration?

Answer 9

[P] total = [P] + [PL]
[L] total = [L] + [PL]

Question 10

Why is the concentration of L roughly the same as the total L concentration?

Answer 10

-[P] total < [L] total
-so [PT] < [L] total
-so [L] roughly [L] total