Hemoglobin And Myoglobin

Question 1

Structure of myoglobin

Answer 1

1 polypeptide chain, 8 alpha helices

Question 2

Structure of Hemoglobin

Answer 2

2 alpha, 2 beta subunits.

Question 3

Proximal Histidine

Answer 3

Binds Fe2+ of heme group to globin, stabilizes the attached heme.

Question 4

Distal Histidine

Answer 4

Prevents oxidation of Fe2+ to Fe3+

Question 5

2,3 Biphosphoglycerate

Answer 5

Facilitates unloading of O2 in capillaries by fitting into central + charged cavity of hemoglobin (stabilizes deoxyhemoglobin)

Question 6

Allosterism

Answer 6

A change in the activity and conformation of an enzyme resulting from the binding of another compound at a site other than the active site.

Question 7

Cooperativity

Answer 7

The principle that the binding of 1 molecule at an active site on one subunit will make it easier for another molecule to bind at an active site on a different subunit due to a conformational change throughout the entire protein from a ‘tensed state’ to a ‘relaxed state’.

Question 8

Is hemoglobin allosteric?

Answer 8

Yes.

Question 9

Is myoglobin allosteric?

Answer 9

No.

Question 10

What is an ethrocyte?

Answer 10

Red blood cell.

Question 11

If pH increases, what happens to the amount of O2 bound?

Answer 11

O2 bound increases

Question 12

If pH decreases, what happens to the amount of O2 bound?

Answer 12

Bound O2 decreases.

Question 13

If [BPG] increases, what happens to O2 bound?

Answer 13

O2 bound decreases.

Question 14

If [BPG] decreases, what happens to O2 bound?

Answer 14

O2 bound increases.

Question 15

Homotropic

Answer 15

When normal ligand are identical to modulators.

Question 16

Heterotropic

Answer 16

When normal ligands differ from modulators.

Question 17

CO2+H2O->?

Answer 17

H+ + HCO3

Question 18

CO2+H2O->HCO3+ H+ is facilitated by what enzyme?

Answer 18

Carbonic anhydrase

Question 19

Why is carbon monoxide so dangerous?

Answer 19

It binds heme groups 200,000 times better than O2, and it binds hemoglobin and myoglobin 200 times better than O2.

Question 20

Where is O2 uptake facilitated, and how?

Answer 20

It’s facilitated in the lungs, where pH is high because there is not enough H+ so the reaction CO2+H2O->HCO3+H+ must be shifted to the left.

Question 21

What is the Bohr Effect?

Answer 21

CO2 effects pH which in turn affects O2s affinity for hemoglobin.