Hemoglobin And Myoglobin Flashcards
Structure of myoglobin
1 polypeptide chain, 8 alpha helices
Structure of Hemoglobin
2 alpha, 2 beta subunits.
Proximal Histidine
Binds Fe2+ of heme group to globin, stabilizes the attached heme.
Distal Histidine
Prevents oxidation of Fe2+ to Fe3+
2,3 Biphosphoglycerate
Facilitates unloading of O2 in capillaries by fitting into central + charged cavity of hemoglobin (stabilizes deoxyhemoglobin)
Allosterism
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.
Cooperativity
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’.
Is hemoglobin allosteric?
Yes.
Is myoglobin allosteric?
No.
What is an ethrocyte?
Red blood cell.
If pH increases, what happens to the amount of O2 bound?
O2 bound increases
If pH decreases, what happens to the amount of O2 bound?
Bound O2 decreases.
If [BPG] increases, what happens to O2 bound?
O2 bound decreases.
If [BPG] decreases, what happens to O2 bound?
O2 bound increases.
Homotropic
When normal ligand are identical to modulators.
Heterotropic
When normal ligands differ from modulators.
CO2+H2O->?
H+ + HCO3
CO2+H2O->HCO3+ H+ is facilitated by what enzyme?
Carbonic anhydrase
Why is carbon monoxide so dangerous?
It binds heme groups 200,000 times better than O2, and it binds hemoglobin and myoglobin 200 times better than O2.
Where is O2 uptake facilitated, and how?
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.
What is the Bohr Effect?
CO2 effects pH which in turn affects O2s affinity for hemoglobin.
