Enzyme catalysis is the increase in the rate of a chemical reaction by the active site of a protein. The protein catalyst (enzyme) may be part of a multi-subunit complex, and/or may transiently or permanently associate with a Cofactor (e.g. adenosine triphosphate).Catalysis of biochemical reactions in the cell is vital due to the very low reaction rates of the uncatalysed reactions.A key driver of protein evolution is the optimization of such catalytic activities via protein dynamics. The mechanism of enzyme catalysis is similar in principle to other types of chemical catalysis.By providing an alternative reaction route the enzyme reduces the energy required to reach the highest energy transition state of the reaction.ovalent catalysis involves the substrate forming a transient covalent bond with residues in the enzyme active site or with a cofactor. This adds an additional covalent intermediate to the reaction, and helps to reduce the energy of later transition states of the reaction.