Enzymes are made from protein, which are made from amino acids. They are catalysts, meaning substances that speed up a reaction (they only speed up a reaction, not make more product). Our body uses enzymes regularly to carry our certain cellular processes in our bodies. Proteins fold uniquely and this allows enzymes to catalyze specific reactions in our bodies. An enzyme attaches to a specific substrate like a lock and key at the active site. The enzyme does its job and then detaches from the substrate back to normal, ready to perform the same task again.

Maltase, lactase, kinase, are some examples of enzymes that speed up processes in our bodies. They can contribute to processes like breaking down certain sugars, DNA replication, or even regulating the cell cycle. They are very important to living things because without them a lot of the processes in our bodies would not go on. It is very important to have a good diet and have proper protein intake to make sure these enzymes are working properly to carry out vital functions.

There are many diseases linked to enzyme inactivity or deficiency like Krabbe disease, Tay-Sach's, Gaucher disease, Fabry disease, and many more.