Endoenzymes and Exoenzymes

 Endoenzymes and Exoenzymes

Enzymes that catalyze biochemical reactions in cells in which they were produced are called endoenzymes or intracellular enzyme. Most of the enzymes involving in the primary and secondary metabolisms of plants are endoenzymes. These enzymes never come out of the cells under normal conditions until the cell wall and plasma membrane are disturbed. After completion of the lifespan, they are destroyed within the cell in which they were produced. Enzymes that catalyze biochemical reactions outside the cells in which they were produced are called exoenzymes or extracellular enzymes. Desmolysing enzymes that breakdown the complex materials outside the cells are all exoenzymes. They are usually secreted by heterotrophic microbes such as bacteria and fungi. Proteases, cellulases, amylases, lipases, etc. are examples for exoenzymes. These enzymes come out of the cell and do catalytic reactions in the cell's environment. Examples-Exoenzymes are usually produced by microbes to hydrolyze insoluble complex food materials in the medium or habitat. Insectivorous plants secrete proteolytic enzymes through its glands on leaves to digest proteins in the prey. In the grains of cereals, the cells of scutellum and aleurone layer secrete hydrolytic enzymes into endosperms to dissolve the stored food materials which are to be made available to germinating seedling.