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What are some characteristics of Hemoglobin?
- Increase Blood O2
What are some characteristics of Myoglobin?
- Detoxifies Nitric Acid (NO to NO3)
What is the general chemical makeup of heme?
- Porphyrin derivative with viyl and methyl priprionate substituents
- Central Fe
What iron oxidization state does Hemoglobin use?
Fractional Saturation of Myoglobin and Hemoglobin...
What does the n stand for in the fractional saturation equation?
- - Mb is 1
- - Hb>1
What is the shape of the Hb binding curve, what does it mean?
Sigmoidal, it means that Hb is cooperative
Binding of one molecule affects binding of other molecules
What interface (α1-α2,β1-β etc) does the main change in Hemoglobin occur?
α1-β2 and β1-α2
How much does β1α1 move by?
Briefly describe the Perutz mechanism of O2 binding
- - O2 binds
- - Fe(II) moves into heme plane
- - Translates Helif F (6A)
What His residue connects heme and helix F?
His F8 (Proximal)
What His residue sits on the opposite side of the heme to the helix F8?
His E7 (Distal)
Describe the α1 β2 interaction upon O2 binding
- The HisFG(97)β2 turn moves along the α1 C helix by one "click" (turn).
- 6 Angstrom shift
When is the R state most stable?
High low fractional saturation (and partial pressure) of O2
When is the T state most stable?
High fractional saturation (and partial pressure) of O2
The "_" residues in the R state are floppy, whereas the same residues in the T state are fixed. What residues, and what fixes the in the T-state?
- α & β C-terminal residues
- Many salt bridges
What does BPG stand for?
How does BPG reduce Hb's O2 affinity?
Binds tightly to the T (deoxy) state
Why is lower O2 affinity beneficial in high altitudes?
Allows more efficient O2 delivery
Where and how does BPG bind?
- Central channel of Hb (same as Cl-)
- Electrostatic interactions