Almost all of the biochemical reactions occurring in an organism and in its metabolic processes are catalyzed by enzymes.
An activated complex acts as an intermediary between the reactants and the products of the reaction. However, it differs from the transition state in that the transition state represents only the highest potential energy configuration of the atoms during the reaction while the activated complex refers to a range of configurations near the transition state that the atoms pass through in the transformation from products to reactants. A chemical reaction is the reorganization of atoms of chemically compatible and chemically reactive molecular compounds, called reactants. This can be visualized in terms of a reaction coordinate, where the transition state is the molecular configuration at the peak of the diagram while the activated complex can refer to any point near the maximum. The energy of the activated complex is higher than that of reactants or the products, and the state is temporary.