A reaction profile includes the activation energy, which is the minimum energy needed by particles when they collide for a reaction to occur. The activation energy is shown as a 'hump' in the line ...

starts at the energy of the reactants is equal to the difference in energy between the top of the 'hump' and the reactants The overall change in energy in a reaction is the difference between the ...

Enzymes lower the activation energy necessary to transform a reactant into a product. On the left is a reaction that is not catalyzed by an enzyme (red), and on the right is one that is (green).