Protein-Ligand Fractional Saturation

Practice: Which of the following statements about protein-ligand binding is correct?

Practice: 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.

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

Practice: 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 = ________

Practice: 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.