8. Protein Function

Consider the following graph for parts A-C.

A) What is the protein-ligand dissociation constant (K_d) for protein X?

a) 2 µM. b) 4 µM. c) 6 µM. d) 8 µM.

B) What is the protein-ligand dissociation constant (K_d) for protein Y?

a) 2 µM. b) 4 µM. c) 6 µM. d) 8 µM.

C) Which protein has a greater affinity for ligand A?

a) Protein X. b) Protein Y.

Match the dissociation constants in the table below to the appropriate curves on the graph.

Use the table below to answer questions A, B & C below.

A) Which protein has a greater affinity for their ligand?

B) According to the data in the table, what is the dissociation constant (K_d) for Protein 1?

Protein 1 K_d = ________

C. According to the data in the table, what is the association constant (K _a) for Protein 2?

Protein 2 K_a = ________

A sample of cells has a total protein-receptor concentration of 10 mM. 25% of the protein-receptors are occupied with ligand when the concentration of free ligand is 15 mM. Calculate the K_d for the receptor-ligand interaction.