Chapter 5: Intro to HG and MG

Question 1

proteins are ____ and tend to have more than ___ structure

Answer 1

dynamic, one

Question 2

protein binding is ______ reversible

Answer 2

specifically

based on chemical interactions

Question 3

a protein can have ____ ligands and multiple _____ spots

Answer 3

multiple, binding

Question 4

simple example of a protein binding a ligand

Answer 4

myoglobin and hemoglobin binding O2

Question 5

myoglobin purpose vs. hemoglobin purpose

Answer 5

myoglobin binds O2 in the muscles

hemoglobin binds O2 in the lungs and transports/releases it in the tissues

Question 6

what prosthetic group does myoglobin and hemoglobin use?

Answer 6

heme (iron Fe2+)

Question 7

what does theta stand for?

Answer 7

the fractional saturation of protein binding sites

it is the # binding sites occupied / total binding sites

Question 8

at a theta of 0.5…

Answer 8

the [L] is equal to the Kd (dissociation constant)

1/2 the binding sites on the protein are occupied

Question 9

mathematical equation to find theta

Answer 9

theta = [L] / ([L] + Kd)

Question 10

on a graph what are the axes?

Answer 10

Y axis is = theta

X axis is [L]

Question 11

in the case of hemoglobin and myoglobin what is the x axis?

Answer 11

p(O2)

partial pressure of O2

Question 12

a smaller Kd =

Answer 12

less [ligand] needed to reach same [PL]

tighter bonding

Question 13

what is Kd

Answer 13

dissociation constant

the physiological [ ] of ligand

Question 14

which protein has the higher affinity for O2?

Answer 14

myoglobin

Question 15

structure of myo vs hemoglobin

Answer 15

myoglobin has 1 protein, 1 high affinity state

hemoglobin is 4 proteins with variable affinities for O2 depending on [O2]

Question 16

high affinity state

Answer 16

denoted by a square

R-state

Question 17

low affinity state

Answer 17

denotes by a circle

T-state

Question 18

O2 regulates…

Answer 18

the function of hemoglobin

example of ligand determining function

high [O2] picks up O2

low [O2] releases O2

Question 19

what happens when hemoglobin binds O2?

Answer 19

the conformation of hemoglobin changes to allow additional easier O2 binding - cooperative binding

heme normally curved, after binding O2 it straightens pushing open alpha helices and O2 binds more easily