DD - Ligand Binding 3 Flashcards
What are the 2 binding events of Kinases?
- Binding of ATP
- Binding of the target protein to be phosphorylated
What occurs to the entropy when a ligand binds to a protein?
Loss of entropy
How can polar binding sites act to increae entropy?
Polar sites can release tightly-bound water molecules on drug binding
What is an agonist?
A chemical that binds to a receptor and activates the receptor to produce a biological response
How do partial agonists differ?
Have only partial efficacy at the receptor
What is an antagonist?
A drug that blocks agonist-mediated responses
What is an inverse agonist?
A ligand that binds to a receptor and decreases response below the basal level
What is Intrinsic activity?
Refers to the relative ability of a drug-receptor complex to produce a maximum functional response
What is potency defined as?
A measure of drug activity expressed in terms of the amount required to produce an effect of given intensity
* (A highly potent drug evokes a response at lower concentrations)
What are 7 methods to measure ligand binding?
- Radioactive ligand binding assays
- Spectroscopy
- Fluorescence
- NMR
- ELISA
- HPLC
- Mass Spectrometry
How does Isothermal Titration Calorimetry (ITC) work?
Works by directly measuring the heat that is either released or absorbed when molecules interact
How can ITCs be used to determine Kd?
- Ligand-containing syringe is continuously injected into the macromolecule-containing sample
- Signal returns to baseline before the next injection
- Gradually, the sample becomes more saturated with the ligand and hence less binding occurs (heat change decreases)
- After no more binding occurs, a graph is drawn and Kd is calculated
What is a Thermal Shift Assay?
Monitors fluorescence of binding to unfolded hydrophobic core of proteins
* Measures protein unfolding
Does the thermal shift assay work with all proteins?
No- Does not work with memrane proteins
