The membrane-bound structure that contains digestive enzymes is the lysosome. Lysosomes contain enzymes that break down organic macromolecules such as carbohydrates, fats and proteins. All animal cells contain lysosomes, but they are most present in the cells of the immune system, such as white blood cells.
About 40 different digestive enzymes reside inside a lysosome. These enzymes are made by organelles called ribosomes that are attached to the endoplasmic reticulum and put into packages by the Golgi bodies. The inside or matrix of a lysosome has an acidic pH of about 4.8, which is the optimal environment for the enzymes. Outside of the lysosome, these enzymes are rendered harmless because the pH there is non-acidic and does not support the normal functioning of lysosomal enzymes.