What is the effect of an enzyme on the equilibrium state of a biochemical reaction? Explain.

Question

What is the effect of an enzyme on the equilibrium state of a biochemical reaction? Explain.

Answer 1

In short, enzymes do not change the equilibrium state of a biochemical reaction.  ΔG⁰ and K_eq remain the same. Instead, the enzyme reduces the activation energy needed for the reaction to proceed, and thus increase the rate of reaction. Say for example, Keq = 1, and you start with reactants only.  Under normal conditions it may take 100 years, but eventually the concentration of reactants will equal the concentration of products.  Now start over, but add an enzyme.  In this case we reach equilibrium in 100 seconds, but it still results in a 1:1 ratio of reactants to products.  

 

Why?  

 

Enzymes work by stabilizing reaction intermediates.  And as such, they catalyze reactions in either direction! Enzymes enhance rates.  They don't change free energy differences nor do the affect equilibrium constants.

Answer 2

In a biochemical reaction a substrate or two substrates react to generate a product. This involves transfer of free energy and  equilibrium is attained. An appropriate enzyme would accelerate the rate of attaining this equilibrium. This is the precise point that may vary depending on the reaction and additional factors such as temperature, pH  and other components.