1.2 Ligand Binding And Cooperarivity Flashcards
What is a ligand
A substance which binds to a protein
R groups can get involved in ligand binding IF
they they are not involved in protein folding
Protein binding sites have complimentary what to the ligand
Shape and chemistry
What changes when a ligand binds to a protein binding site, and what effect does this have on the protein
The conformation of the protein changes
A functional change in the protein
Define ‘allosteric’ interactions
Interactions which occur between spatially distinct sites
What do modulators do
Regulate the activity of the enzyme when they bind to the allosteric site
What are the two types of modulators and what do they do
Positive modulators: activate
Negative modulators: inhibit
Define cooperativity in binding
Changes in binding at one subunit alter the affinity of the remaining subunits
Give an example of cooperativity
The binding and release of oxygen in haemoglobin
As oxygen binds, it’s affinity for it at the other subunits is higher
Oxygen dissociation curve: what affects the binding of oxygen to haemoglobin
pH and temperature
What effect does a decrease in pH have on the affinity of haemoglobin for oxygen
Lowers the affinity
Binding is reduced
What effect does an increase in temperature have on the affinity of haemoglobin for oxygen
Lowers the affinity
Binding is decreased
What effect does a decrease in temperature have on the affinity of haemoglobin for oxygen
Increase the binding
Higher affinity
What effect does an increase in pH have on the affinity of haemoglobin for oxygen
More binding
Higher affinity
