What Are the Functions of the Protease Enzyme?

In general chemistry terms, an enzyme is a catalyst--that is, a substance which affects the course of a chemical reaction without being changed itself. Within the human body, the enzyme protease catalyzes a number of important functions, ranging from protein digestion to the replication of HIV in the blood of those infected with it.

Protein digestion

• All enzyme names end with the suffix "-ase," so it should come as no surprise that protease's primary function involves protein. Specifically, as Enzyme Essentials explains, it "breaks down the peptide bonds in the protein foods to liberate the amino acids needed by the body" in a process known as hydrolysis. (

  So what stops protease from breaking down human cells made of protein--muscles, for example? The website goes on to clarify that "normal living cells are protected against lysis by the inhibitor mechanism."

HIV replication

• This is not to say that all protease enzymes serve welcome functions. One example of this occurs in the case of HIV, the Human Immunodeficiency Virus. After someone is infected with HIV, RNA within existing viruses produces long polypeptide protein chains, which so-called viral protease must then hydrolyze at certain points along its length into order to catalyze the manufacture of additional viruses.

  For this reason, drugs called protease inhibitors, which block the function of viral protease, are becoming commonplace in the fight against HIV.

Auxiliary functions

• According to Enzyme Essentials, protease is important in maintaining the pH balance of the blood because "acidity is created through the digestion of protein." If someone lacks the quantities of protease his body requires," the website explains, it can "result in an alkaline excess in the bloodstream."

  Protease's digestive prowess doesn't just cover food. It can also "digest unwanted debris in the blood including certain bacteria and viruses."