Unit 1.2.c.ii Flashcards
What is a ligand?
A substance that can bind to a protein
What do R groups who are not involved in protein folding do
Bind to ligands
Binding sites will have (1) and chemistry to the (2)
- Complementary shape
2. Ligand
What happens to the protein as a ligand binds to a protein-binding site
The conformation of the protein changes and this causes a functional change in the protein
When do allosteric interactions occur?
Between spatially distinct sites
How does the binding of a substrate molecule to 1 active site of an allosteric enzyme affect the enzyme
Increases the affinity of the other active sites for binding of subsequent substrate molecules. This is of biological importance because the activity of allosteric enzymes can vary greatly with small changes in substrate concentration.
What do many allosteric proteins consist of? What does this show?
Multiple subunits (have quaternary structure)
Co-operativity in binding in which changes in binding at one subunit alters the affinity of the remaining subunits
What is the second type of site an allosteric enzyme possesses
An allosteric site
______ regulate the activity of the enzyme when they bind to the allosteric site
Modulators
What happens following the binding of a modulator
The conformation of the enzyme changes and this alters the affinity of the active site for the substrate
What is the difference between positive and negative modulators
Positive modulators increase the enzyme’s affinity for the substrate, whereas negative modulators reduce the enzyme’s affinity
What does the binding and release of oxygen in haemoglobin show?
Co-operativity
Changes in binding of oxygen at one subunit alter the affinity of the remaining subunits for oxygen
What is the influence and physiological importance of temperature and pH on the binding of oxygen?
A decrease in pH or an increase in temperature lowers the affinity of haemoglobin for oxygen, so the binding of oxygen is reduced. Reduced pH and increased temperature in actively respiring tissue will reduce the binding of oxygen to haemoglobin promoting increased oxygen delivery to tissue.
