2.3 Protein Structure, Ligand Binding and Conformational Change ii Ligand Binding Changes the Conformation of a Protein Flashcards
What is a ligand?
A substance that can bind to a protein
Which molecule allows binding to ligands?
R groups that are not involved in protein folding
What about a ligand’s binding site is described as complimentary?
Shape and chemistry
What changes about a protein once a ligand binds to a ligand- binding site?
Conformation
What does a change in the shape of a protein result in?
This change in conformation causes a functional change in the protein
Where do allosteric interactions occur?
Between spatially distinct sites
The binding of a substrate molecule to one active site of an allosteric enzyme does what to the affinity of the other active sites
Increases the affinity of the other active sites for binding of subsequent substrate molecules.
How can the activity of allosteric enzymes vary?
Small changes in substrate concentration causes a great variation in activity.
What kind of structure do most allosteric proteins have?
Quaternary structure (consist of multiple subunits)
What do allosteric proteins show when binding?
co-operativity, in which changes in binding at one subunit alter the affinity of the remaining subunits
What is the second type of site found on an allosteric enzyme called
Allosteric site
What is the purpose of a modulator?
Modulators regulate the activity of the enzyme
Where do modulators bind to?
The allosteric site
What happens once a modulator has bound to the enzyme?
Following binding of a modulator, the conformation of the enzyme changes and this alters the affinity of the active site for the substrate
Effect of a positive modulator
Positive modulators increase the enzyme’s affinity for the substrate
