Catalyst

A catalyst is a substance that alters the activation energy of a chemical reaction, thus facilitating its occurrence, but does not get consumed in the process. A protein that acts as a catalyst is called an enzyme. An example of catalysis is the action of Manganese oxide on the decomposition of Hydrogen Peroxide. Heterozygous catalysis occurs when catalyst and reactant(s) are in the same phase whereas homozyous catalyis is when they are in different phases.