The small molecules, generated by the exoenzyme activity, enter into cells and are utilized for various cellular functions. Very limited information is available enzymes are classified as macromolecules known as the original discovery of exoenzymes. The book “Intracellular Enzymes: A Course of Lectures Given in the Physiological,” by Horace Vernon is thought to be the first publication using this word in that year. Vernon to have been discovered by scientists Briike and Kiihne before 1908. Many bacteria use digestive enzymes to break down nutrients in their surroundings.