- #1
TytoAlba95
- 132
- 19
I was stuck with a question; how does enzyme lower the activation energy of a reaction. After several internet searches, I found a post in biostackexchange which partially clarified my question. I'll write my current understanding before I proceed to my actual question.
Activation energy is the energy required by reactants to reach a transition state. The transition state is a state of reactants in which old bonds are being broken and new bonds are being formed (say its a nucleophile substitution reaction). To reach this state, energy is needed (supplied in the form of heat). This heat energy is utilized to increase the kinetic energy of the molecules, such that the reactant molecules collide with each other in the proper orientation to form the T.S. (Not all molecules will have the sufficient energy or orientation to collide and form T.S.)
Now once the T.S. is formed it can either breakdown into products or reactants.
In case of an enzyme, the interaction of the reactants with the active site brings the reactant molecules close together and in the proper orientation for the T.S to form. Thus the energy needed for the reactant molecules to get converted into T.S (or product) is lowered.
As the conversion occurs pretty much automatically at the active site in normal physiological temperature, I do not understand why should there be any activation energy at all for enzyme catalysed reactions. Or maybe, I should say in what ways the reactants take up energy in enzymatic reactions.
Activation energy is the energy required by reactants to reach a transition state. The transition state is a state of reactants in which old bonds are being broken and new bonds are being formed (say its a nucleophile substitution reaction). To reach this state, energy is needed (supplied in the form of heat). This heat energy is utilized to increase the kinetic energy of the molecules, such that the reactant molecules collide with each other in the proper orientation to form the T.S. (Not all molecules will have the sufficient energy or orientation to collide and form T.S.)
Now once the T.S. is formed it can either breakdown into products or reactants.
In case of an enzyme, the interaction of the reactants with the active site brings the reactant molecules close together and in the proper orientation for the T.S to form. Thus the energy needed for the reactant molecules to get converted into T.S (or product) is lowered.
As the conversion occurs pretty much automatically at the active site in normal physiological temperature, I do not understand why should there be any activation energy at all for enzyme catalysed reactions. Or maybe, I should say in what ways the reactants take up energy in enzymatic reactions.