Protease

A protease, also called a peptidase, proteinase, or proteolytic enzyme, is any enzyme that catalyzes the hydrolysis of peptide bonds, thereby cutting proteins into shorter peptides or free amino acids ^[1]. Proteases are classified by the catalytic mechanism they use, and biochemists recognize several major types named for the key chemical group in the active site: serine, cysteine, threonine, aspartic, glutamic, and metalloproteases, along with the asparagine peptide lyases, which break the bond by an elimination reaction rather than by adding water ^[1]. Under the enzyme numbering system they fall within class EC 3.4, the hydrolases that act on peptide bonds, and databases such as MEROPS further sort them into dozens of clans that each represent a separate evolutionary origin of proteolytic activity ^[1].

Proteases are found across all forms of life, from bacteria and viruses to plants and animals, and they take part in a remarkable range of biological processes ^[1]. In the human digestive tract, pepsin begins protein breakdown in the acidic stomach, while trypsin and chymotrypsin continue it in the small intestine. Beyond digestion, proteases regulate blood clotting and its dissolution, activate hormones and other signalling molecules, dispose of damaged proteins, and help control the immune response and programmed cell death ^[1]. Because proteolysis is essentially irreversible, its activity is tightly controlled in the body, and dysregulated proteases are implicated in conditions such as cancer, inflammation, and neurodegeneration ^[1].

Proteases have wide practical use. Industrially they appear in laundry detergents, in cheese-making, and as processing aids in the food industry, and specific proteases such as TEV protease are standard tools in molecular biology ^[1]. As supplements and medicines, proteolytic enzymes are taken to aid digestion. People with exocrine pancreatic insufficiency, in which the pancreas cannot supply enough digestive enzymes, are treated with pancreatic enzyme replacement therapy that includes proteases alongside enzymes for fat and starch ^[3]. Researchers have also explored bacterial and fungal proteases known as glutenases as a way to break down the gluten peptides that trigger celiac disease, with several enzyme products tested in clinical studies ^[2]. Common supplemental proteases include plant-derived enzymes such as bromelain from pineapple and papain from papaya, as well as fungal and pancreatic preparations.

When taken to correct pancreatic insufficiency, protease-containing enzyme products are regulated as prescription medicines, whereas general-purpose digestive enzyme blends are widely sold as over-the-counter dietary supplements ^[3]. Supplemental proteases are available in capsules, tablets, and powders, sometimes with an enteric coating designed to protect the enzymes from stomach acid so that more of the activity reaches the intestine.

Generally well tolerated. Main sides are GI upset, and bromelain/papain can trigger allergic reactions, especially in people allergic to pineapple or latex. Proteases can have mild blood-thinning effects, so caution around surgery or with anticoagulants.