Trypsin inhibitors are chemicals that reduce the availability of trypsin

Trypsin

Trypsin is a serine protease found in the digestive system of many vertebrates, where it hydrolyses proteins. Trypsin is produced in the pancreas as the inactive proenzyme trypsinogen. Trypsin cleaves peptide chains mainly at the carboxyl side of the amino acids lysine or arginine, except when...

, an enzyme

Enzyme

Enzymes are proteins that catalyze chemical reactions. In enzymatic reactions, the molecules at the beginning of the process, called substrates, are converted into different molecules, called products. Almost all chemical reactions in a biological cell need enzymes in order to occur at rates...

 essential to nutrition

Nutrition

Nutrition is the provision, to cells and organisms, of the materials necessary to support life. Many common health problems can be prevented or alleviated with a healthy diet....

 of many animal

Animal

Animals are a major group of multicellular, eukaryotic organisms of the kingdom Animalia or Metazoa. Their body plan eventually becomes fixed as they develop, although some undergo a process of metamorphosis later on in their life. Most animals are motile, meaning they can move spontaneously and...

s, including human

Human

Humans are the only living species in the Homo genus...

s.

There are four commercial sources of trypsin inhibitors.

Source	Molecular weight	Inhibitatory power	Details
Serum Blood plasma Blood plasma is the straw-colored liquid component of blood in which the blood cells in whole blood are normally suspended. It makes up about 55% of the total blood volume. It is the intravascular fluid part of extracellular fluid...  (α1-antitrypsin Alpha 1-antitrypsin Alpha 1-Antitrypsin or α1-antitrypsin is a protease inhibitor belonging to the serpin superfamily. It is generally known as serum trypsin inhibitor. Alpha 1-antitrypsin is also referred to as alpha-1 proteinase inhibitor because it inhibits a wide variety of proteases... )	52 kDa		Also known as serum trypsin inhibitor
Lima beans	8-10 kDa	2.2 times weight	There are six different lima bean Lima bean Phaseolus lunatus is a legume. It is grown for its seed, which is eaten as a vegetable. It is commonly known as the lima bean or butter bean.-Origin and uses:...  inhibitors.
Bovine pancreas Pancreas The pancreas is a gland organ in the digestive and endocrine system of vertebrates. It is both an endocrine gland producing several important hormones, including insulin, glucagon, and somatostatin, as well as a digestive organ, secreting pancreatic juice containing digestive enzymes that assist...	6.5 kDa	2.5 times weight	Kunitz inhibitor, or BPTI (basic pancreatic trypsin inhibitor, is the best known pancreatic Pancreas The pancreas is a gland organ in the digestive and endocrine system of vertebrates. It is both an endocrine gland producing several important hormones, including insulin, glucagon, and somatostatin, as well as a digestive organ, secreting pancreatic juice containing digestive enzymes that assist...  inhibitor. Chymotrypsin Chymotrypsin Chymotrypsin is a digestive enzyme that can perform proteolysis. Chymotrypsin preferentially cleaves peptide amide bonds where the carboxyl side of the amide bond is a tyrosine, tryptophan, or phenylalanine. These amino acids contain an aromatic ring in their sidechain that fits into a...  is also inhibited by this chemical, but less tightly. When extracted from lung tissue, this is known as aprotinin Aprotinin The drug aprotinin , is the bovine version of the small protein basic pancreatic trypsin inhibitor, or BPTI, which inhibits trypsin and related proteolytic enzymes. Under the trade name Trasylol, aprotinin was used as a medication administered by injection to reduce bleeding during complex surgery,... .
Ovomucoid	8-10 kDa	1.2 times weight	Ovomucoids are the glycoprotein Glycoprotein Glycoproteins are proteins that contain oligosaccharide chains covalently attached to polypeptide side-chains. The carbohydrate is attached to the protein in a cotranslational or posttranslational modification. This process is known as glycosylation. In proteins that have segments extending...  protease Protease A protease is any enzyme that conducts proteolysis, that is, begins protein catabolism by hydrolysis of the peptide bonds that link amino acids together in the polypeptide chain forming the protein....  inhibitors found in raw avian egg white. There are other protease inhibitors in ovomucoids as well.
Soybean Soybean The soybean or soya bean is a species of legume native to East Asia, widely grown for its edible bean which has numerous uses... s	20.7-22.3 kDa	1.2 times weight	Soybeans contain several inhibitors; the one in the chart is considered the primary one. All of them bind chymotrypsin to a lesser degree.

A study revealing that proteinase inhibitor from the eggs of the freshwater snail

Freshwater snail

A freshwater snail is one kind of freshwater mollusc, the other kind being freshwater clams and mussels, i.e. freshwater bivalves. Specifically a freshwater snail is a gastropod that lives in a watery non-marine habitat. The majority of freshwater gastropods have a shell, with very few exceptions....

 Pomacea canaliculata

Pomacea canaliculata

Pomacea canaliculata, common name the channeled applesnail, is a species of large freshwater snail with gills and an operculum, an aquatic gastropod mollusk in the family Ampullariidae, the apple snails....

, interacts as a trypsin inhibitor with the protease of potential predators, was reported in 2010, the first direct evidence for this mechanism in the animal kingdom.