2cii + ciii: Ligands, Conformational Changes, And Phosphorylation Flashcards
What is an allosteric enzyme
enzymes with a second type of site called the allosteric site
What does a modulator do
regulate the activity of the enzyme when they bind to the allosteric site
What happens after the binding of a modulator
the conformation on an enzyme changes and this alters the affinity of the active site for the substrate
positive modulator function
increase the enzymes affinity for the substrate
negative modulator function
decrease the enzymes affinity for the substrate
allosteric proteins with multiple subunits show…
show co-operativity in binding, in which changes in binding at one subunit alter the affinity of the remaining subunits
What is phosphorylation
A common form of post- translational modification.
The addition or removal of phosphate can cause reversible conformational changes in proteins.
Some proteins are activated by phosphorylation whilst others are inhibited
What does kinase do
Kinase catalyses the transfer of a phosphate to other proteins
(Adds phosphate to proteins from ATP)
Kinase transfers the terminal phosphate of ATP to…
Specific R groups in a protein
What will adding a phosphate to a protein do to the charge
Adds a negative charge.
Ionic interactions in the unphosphorylated protein can be disrupted and new ones created.
What does phosphatase do
Catalyses the reverse reaction. (Dephosphorylation)
Removes the phosphate.
Why are ligand binding sites on a protein specific to a ligand
They have complementary shape and chemistry to the ligand.
What can R groups not involved with protein folding can allow
Binding to ligands
