Trypsin molecule. Computer model of a molecule of the digestive enzyme trypsin. Trypsin is a complex protein, released by the pancreas to break down proteins into smaller chains of amino acids (a protease). It is released in an inactive form (trypsinogen) and converted to trypsin in the small intestine by the action of the enzyme enterokinase. The molecule is colour-coded: blue represents the amino acids alanine, lysine and arginine, and the red represents everything else.