Question

A small molecule inhibitor of a protein is designed, and when the two are mixed in equimolar amounts, and the system is allowed to reach equilibrium, you measure the concentrations of solution components as follows: [Protein]: 120 µM, [Inhibitor]: 120 µM, [Protein-Inhibitor Complex]: 1.5 mM. Calculate the association constant and dissociation constant for this binding interaction

2. A small molecule inhibitor of a protein is designed, and when the two are mixed in equimolar amounts, and the system is allowed to reach equilibrium, you measure the concentrations of solution components as follows: [Protein] 120 HM, [Inhibitor]: 120 HM [Protein-Inhibitor Complex] 1.5 mM. Calculate the association constant and dissociation constant for this binding interaction. (8 points)

Answer 1

Protein + Protein-Inhibitor Complex Inhibitor Inhibitor T 120 x 10-6M K" Equilibrium concentration: 120 x 10-6 M 1.5 x 10-3M 1. Equilibrium constant related to the formation of Protein-Inhibitor Complex is K & is called association constant 2. Equilibrium constant related to the dissociation of Protein-Inhibitor Complex is K" & is called dissociation constant According to law of chemical equilibrium/law of mass action; [Protein-Inhibitor complex] [Protein] [Inhibitor] K= & K": [Protein) [Inhibitor) [Protein-Inhibitor complex] K= 1.5 x 10-3 120 x 100 x 120 x 10-6 & 100 x 100 K" = 9.5997 x 10-6 K - = 1.0417 x 103 K= Association constant = 1.0417 x 105 K" = Dissociation constant = 9.5997 x 10-6