Toward the Hill hot mess

Question 1

What is the basic definition of Ka?

Answer 1

The affinity or association constant… so the number of bound enzymes over the construction of just enzymes X just substrate

Question 2

What is the basic definition of Kd?

Answer 2

the dissociation constant.. breaking apart… The product of the concentrations of enzymes and substrates over the bound enzyme concentration

HALF of the binding sites are full

Question 3

Describe fractional saturation (Y)

Answer 3

the total fraction of the protein that contain a ligand

bound/bound+unbound (total)

Question 4

Give the equation for Y (fractional saturation)

Answer 4

[S]/ Kd + [S]

Question 5

When would you use a scatchard plot?

Answer 5

If you have an n=1 scenario, so one binding site.

Originally the graph of n=1 is hyperbolic but you want to see what Kd is, which is where half of the ish is saturated

So you use it to find the Kd basically

Question 6

what is the scatchard plot equation?

Answer 6

[ES]= -(1/Kd) [ES] + ([E]/Kd)

Question 7

What is the slope of a Scatchard plot?

Answer 7

-1/Kd

Question 8

What is the y-intercept of a Scatchard plot?

Answer 8

1/Kd

Question 9

What is the X intercept of a Scatchard plot?

Answer 9

[E]t

Question 10

Define cooperativity

Answer 10

Binding of each subsequent ligand influences the binding of the next ligand….
ie peer pressure

Question 11

When you have more than one binding site, what is the equation for theta? (The Y in the more than one binding site situation)

Answer 11

theta= [S]^n / Kd + [S]^n

Question 12

What is the Hill coefficient

Answer 12

The nH in the theta equation; represents the number of binding sites

Question 13

What is the Hill equation (to make a linear plot)

Answer 13

log ( theta / 1-theta)= log(1/Kd) + nH(log[S])

Question 14

What is the slope of the Hill plot?

Answer 14

nH; the number of binding sites

Question 15

What is the y intercept of a Hill plot?

Answer 15

log (1/Kd)

Question 16

If nH= 1, what does that say about the cooperativity of the molecules?

Answer 16

There is NO cooperativity, the sites are independent

Question 17

If nH > 1, what does that say about the cooperativity of the molecules?

Answer 17

positive cooperativity, affinity increases

Question 18

If nH<1, what does that say about the cooperativity of the molecules?

Answer 18

negative cooperativity; affinity decreases

Question 19

What would you expect the nH of hemoglobin to be? What is the actual nH of hemoglobin?

Answer 19

you expect 4 but get 2.8