Module 14 Flashcards
Ligands
Oxygen
Carbon Monoxide
Carbon Dioxide
Cyanide (cytochromes)
What is cooperative binding?
a process where the binding of a ligand to one site on a protein changes the affinity of other binding sites for that ligand
Characteristics of myoglobin oxygen binding
Monomeric
Non-cooperative binding
Higher affinity for oxygen
Holds onto oxygen supply until levels in muscles are very low
Characteristics of hemoglobin oxygen binding
Tetrameric
Cooperative binding
Oxygen affinity increases as more oxygen is bound to heme
When does myoglobin release oxygen?
When the concentration of oxygen drops to very low levels
Hemoglobin has what kind of curve?
Sigmoidal curve–> cooperative binding
Oxygen affinity ______ as more oxygen is bound to heme
increases
Myoglobin curve is more further to the ______
left
Sigmoidal shape reflects what type of binding?
cooperative
What is happening to the structure of the protein itself that increases its affinity to bind to oxygen?
Conformational change
Fetal hemoglobin has a ______ affinity for oxygen than adult hemoglobin
higher
BPG or 2,3-biphosphoglycerate binding
binds well to adult hemoglobin, but weakly or not at all to fetal hemoglobin
What intermolecular force does BPG have with adult hemoglobin?
ion-ion , histadine ring present, closer together
What intermolecular force does BPG have with fetal hemoglobin?
very weak binding, further apart
BPG is a _______ inhibitor
competitive
BPG _______ oxygen affinity by shifting equilibrium to the _______.
lowers, left,
favoring the T state and deoxyhemoglobin
Carbon dioxide transport occurs by one of three mechanisms:
- Dissolved gas
- Bicarbonate -majority is transported via this method
- Bound to the protein of hemoglobin- carbaminohemoglobin
How much more soluble in plasma is Co2 than O2?
20 times more soluble
What is the percent of Co2 that is dissolved?
10%
Bohr Effect
The effect of pH on hemoglobins affinity for oxygen
-A decrease in pH causes the bohr effect, which reduces hemoglobins affiniity for oxygen.
-This is represented as a shift to the RIGHT on the oxygen dissociation curve
Haldane effect
The effect of oxygenation on hemoglobins’ affinity for carbon dioxide
-an increase in oxygenation causes the Haldane effect, which reduces the amount of carbon dioxide in hemoglobin
-this helps remove carbon dioxide from venous blood in the lungs
Oxygen dissociation is altered by the following changes to the chemical environment:
Increasing temperature
Lowering blood pH
Increasing partial PCO2
What do we see with increasing partial Pco2?
Increases hydrogen ion concentration
Protonates certain amino acid residues
Leads to conformation change of protein
Carbon monoxide binds how much more strongly than oxygen?
200-300 times more strongly
Carbon monoxide (CO) prevents what from binding to hemoglobin?
oxygen
it also limits the transport of oxygen to tissue
How can we help unbind CO (carbon monoxide) ligand to hemoglobin?
Increasing O2 pressure allows CO to be kicked off
Binding is _______.
reversible
