Globin Proteins And Properties

Question 1

Myoglobin structure and function

Answer 1

O2 storage in the muscles for times of low pO2/stress.

Located in cytoskeleton of muscle cells.

Contains one heme .

Made of 8a helices.

Question 2

Cooperativity Hill coefficient- ?

Answer 2

Myoglobin=1, Hb = 2.8

N=4 would mean all in complete concert.

Question 3

What factors stabilize the R state?

Answer 3

O2 binding

High pH

NO

Question 4

What factors stabilize the T state?

Answer 4

CO2, BPG, acidic blood (low pH)

Question 5

Why is T state less favorable to O2 binding?

Answer 5

More salt bridges exist in T state, and these stabilize a conformational change that is less favorable to O2 binding:

Fe2+ is out of the plane of the heme ring, and bends heme.

Question 6

CO poisoning

Answer 6

CO has a greater affinity for Hb than O2. Bound heme is slightly less so. High levels of COHb are bad.

Produces red skin and organs. Treated with 100% O2.

Question 7

Effect of pH on Hb O2 affinity

Answer 7

Lowering pH lowers affinity of Hb for O2.