Lysosomes were described by the Belgian cytologist Christian René de Duve in the 1950s. Lysosomes are single-membrane-bound organelles found in many human cells. They are small vesicles (ranging in size from 0.1 to 0.5 μm) of fluid, with the lumen’s pH about 4.5–5.0 (similar that surrounded by a lipid bilayer membrane that helps to keep the enzymes separate from the rest of the cell, protecting the cell from destruction. Typically, a mammalian cell contains around 300 (ranging 50–1000) of this organelle [1] (Fig. 1.1).