*Receptor Theory 1 Flashcards
Binding, Affinity and Agonists
where do drugs bind?
to specific receptors
- The drug (ligand) with the higher affinity is more specific for that receptor
what 3 factors control drug binding? explain each
Speed of drug reaching receptor is diffusion controlled
electrostatic, hydrophobic, and hydrogen bonds allow drug to “fit” into binding site
Binding is a dynamic equilibrium in other words the drug does not remain bound forever
how do electrostatic forces impact drug binding?
the ligand (drug) and the receptor must have opposite charges to ensure they are attracted to one another
how do hydrophobic forces impact drug binding?
if the ligand (drug) is polar the receptor must also be polar
if the ligand is lipophilic the receptor must also be lipophilic
how does the “Shape” of molecule and binding site impact drug binding?
the drug must have the male shape when the recptor has the identical female shape so they fit together
- Just like certain keys only fit in certain locks
what is a ligand binding assay?
a laboratory procedure that measures the interaction between a ligand and a receptor
what is the word equation for a ligand binding assay?
L+R <–> LR
- where L is the ligand
- R is the receptor
- LR is the ligand-receptor complex
what is the binding constant or affinity constant?
a measure of how strongly the ligand and receptor bind to each other.
how is the binding constant measured?
It’s calculated using the equilibrium dissociation constant (Kd), which is the ratio of the concentrations of the ligand and receptor to the concentration of the ligand-receptor complex.
what does high affinity mean in terms of drug binding?
tightly fitting
what are non-specific receptor sites?
molecular sites that bind to ligands but are not designated as receptors
(will bind loosely)
- lots of them, with many different structures
L + R <–> LR shows what?
binding at equilibrium.
- the number of ligands binding = the number unbinding
up to slide 28
