Hemoglobin and Allostery Flashcards
Which line is Hb vs Mb?
Explain why we need Hb to have a S-shaped curve.
It’s due to Cooperatively and oxygen binding.
This shape is needed because the role of Hb is to carry oxygen to muscles/organs far away from the lungs.
Needs to be able to fill up high when next to heart(arterial pressure).
Needs to be able to release oxygen near muscles(venous pressure).
Do you understand why myoglobin wouldn’t work?
What is the Hill equation?
Way to quantify the cooperative binding interactions of hemoglobin S-shaped curve. (Higher the coefficient the steeper the S curve)
What is the Bohr effect? Why is it an effect?
pH sensitivity of oxygen binding to hemoglobin.
Because Hemoglobin structure relies of salt bridges (very strong noncovalent interactions) . pH messes with noncovalent interactions!
Explain exactly how pH affects oxygen delivery through hemoglobin.
Deoxygenated state of hemoglobin (T-state) relies on salt bridges. One being through histamine(pKa 6).
As pH gets lower, histamine gets protonated, making it more favorable to form salt bridges = more favorable for Hb to be in T-state. (Lower pH = lower affinity O2 has to Hb)
Why is the Bohr effect good? (Why is lower pH good for Hb?)
Good because allows the parts of the body that are farther away from the lungs to use a lower pH environment to get more oxygen out of Hb.
Define Allosteric effect.
- The binding of one ligand at one site affects the binding of another ligand at another site.
- Often, but not necessarily always, requires interactions between subunits of oligomeric proteins.
There are four models of allosteric, transitions and hemoglobin for this class, which one matters for hemoglobin allostery specifically ?
Matters: Symmetry model
Other 3:
1. Sequential Model
2. Multistate Model: complex, combining features of sequential and symmetry models.
3. Dynamic Model: changes due to dynamic properties rather than confirmational changes per se.
Explain the allosteric proteins - symmetric model.
Explain allosteric proteins- Sequential model
What is BPG?
- Where does BPG bind in hemoglobin?
- What state does it bind to?
- When does BPG increase?
- What is the net effect of BPG?
Makes hemoglobin just as effective at delivering oxygen at high altitude as it is at sea level.
Which line on the graph has high vs normal BPG levels?
