Problem: A chemist at a pharmaceutical company is measuring equilibrium constants for reactions in which drug candidate molecules bind to a protein involved in cancer. The drug molecules bind the protein in a 1:1 ratio to form a drug-protein complex. The protein concentration in aqueous solution at 25 oC is 1.72×10−6 M. Drug A is introduced into the protein solution at an initial concentration of 2.00 10-6 M. Drug B is introduced into a separate, identical protein solution at an initial concentration of 2.00 10-6 M. At equilibrium, the drug A-protein solution has an A-protein complex concentration of 1.00 10-6 M, and the drug B solution has a B-protein complex concentration of 1.40 10-6 M.Calculate the Kc value for the B-protein binding reaction.

FREE Expert Solution

In this problem, we are asked to calculate the equilibrium constant, Kc value for the B-Protein binding process.


When dealing with equilibrium and Kc:

Kc → equilibrium units are in molarity 
Kc is an equilibrium expression:

Kc=productsreactants

only aqueous and gaseous species are included in the equilibrium expression
▪ the coefficient of each compound in the reaction equation will be the exponent of the concentrations in the equilibrium expression 

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Problem Details

A chemist at a pharmaceutical company is measuring equilibrium constants for reactions in which drug candidate molecules bind to a protein involved in cancer. The drug molecules bind the protein in a 1:1 ratio to form a drug-protein complex. The protein concentration in aqueous solution at 25 oC is 1.72×10−6 M. Drug A is introduced into the protein solution at an initial concentration of 2.00 10-6 M. Drug B is introduced into a separate, identical protein solution at an initial concentration of 2.00 10-6 M. At equilibrium, the drug A-protein solution has an A-protein complex concentration of 1.00 10-6 M, and the drug B solution has a B-protein complex concentration of 1.40 10-6 M.

Calculate the Kc value for the B-protein binding reaction.

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