The special type of protein that accelerates the speed of reaction by existing in small amounts in various types of biochemical reactions and remains unchanged subject to certain conditions at the end of the reaction is called enzyme. Enzymes are called biocatalysts. About 4,500 types of enzymes have been discovered so far. Enzymes are known as biocatalysts, cell ferments, monocatalysts, bio-regulators, life agents etc. The study of enzymes is called Enzymology.