Elm 4 Competition Binding Flashcards
Q: What is the Gaddum equation used for?
A: The Gaddum equation is used to describe competitive binding between a drug and a competing ligand at a receptor site.
Q: What do the terms KD and Ki represent in the Gaddum equation?
A: KD represents the equilibrium dissociation constant for the drug, while Ki represents the equilibrium dissociation constant for the competing ligand.
Q: How is the Gaddum equation applied in radioligand binding experiments?
A: It helps predict the binding of a drug when its interaction with the receptor can be measured, by considering the competition between the drug and a competing ligand.
Q: What is the purpose of the competition binding equation?
A: The competition binding equation is used to analyze competition binding data and calculate the affinity of drugs by expressing binding values as a percentage of control binding.
Q: How is the Cheng-Prusoff equation used to convert IC50 to Ki?
A: The Cheng-Prusoff equation rearranges the relationship between IC50 and Ki to calculate the equilibrium dissociation constant Ki from the half-maximal inhibitory concentration IC50.
Q: What is the significance of the “p” notation in pharmacology?
A: The “p” notation indicates the negative logarithm of a value, commonly used to express equilibrium dissociation constants (KD) and inhibition constants (Ki) as pKD and pKi, respectively.
Q: How are pKD and pKi values interpreted in pharmacology?
A: Higher pKD and pKi values indicate higher affinity of the drug for its target, as they represent the negative logarithm of the equilibrium dissociation constants KD and Ki, respectively.
Q: What limitation do radioligand binding assays have in drug discovery?
A: Radioligand binding assays only provide information about drug affinity and cannot provide insights into downstream effects or mechanisms of action after drug binding.
Q: What are some advantages of radioligand binding assays in drug discovery?
A: Radioligand binding assays are cost-effective, versatile, and require only one radioligand for each receptor type, making them suitable for early stages of drug discovery.
Q: What are some common radioisotopes used in radioligand binding assays?
A: Common radioisotopes include 3H, 14C, and 125I, which are often used to label radioligands for binding experiments.
