Pepsin

Pepsin is an enzyme. It acts on proteins in the stomach, which has a low pH because of the Hydrochloric acid. It works best at a pH of about 1.5. It will not work at a pH above 6. 

It was the first animal enzyme to be discovered. Theodor Schwann discovered it in 1836.

Pepsin is used to make cheese.

References

Category:Metabolism
Category:Enzymes