Question

Enzyme catalyzed reaction proceed at rates vastly higher than that of uncatalysed reactions. prove this statement by taking a proper example.

Answer 1

In order for a reaction to occur, reactant molecules must contain sufficient energy to cross a potential energy barrier, the activation energy.

The lower the potential energy barrier to the reaction, the more reactants have sufficient energy and, hence, the faster the reaction will occur. All catalysts, including enzymes, function by forming a transition state, with the reactants, of lower free energy than would be found in the uncatalysed reaction. Even quite modest reductions in this potential energy barrier may produce large increases in the rate of reaction.

For e.g., the activation energy for the uncatalysed breakdown of hydrogen peroxide to oxygen and water is 76 kJ M-1 whereas, in the presence of the enzyme catalase, this is reduced to 30 kJ M-1 and the rate of reaction is increased by a factor of 108, sufficient to convert a reaction time measured in years into one measured in seconds.