Energy of Activation
The questions arise here, how enzymes are able to accomplish such effective catalysis and why thermodynamically favourable reactions do not proceed on their own at relatively rapid rates in the absence of enzyme? Chemical transformation requires that certain covalent bonds be broken within the reactants. To do so the reactants must contain sufficient kinetic energy (energy of motion) to overcome a barrier called Energy of activation or Activation energy. The important role played by the enzymes during reactions is that they lower the activation energy of the reaction. The enzyme reacts with the energy rich and energy poor molecules to form an intermediate complex. This complex again breaks into product and enzyme. If activation energy of this complex is low, many molecules can participate in reaction. In this way activation energy is lowered by the enzyme but in this action equilibrium (ratio of concentration of reactant and product) is never altered, it remains the same.