Chymotrypsin (EC 3.4.21.1) is a key serine protease involved in dietary protein digestion in mammals. It is primarily produced by the pancreas, but may be expressed in other tissues, including spleen and liver. In the pancreas, chymotrypsin is initially expressed as the inactive proenzyme chymotrypsinogen, which is cleaved by other proteases to chymotrypsin, its active form. Chymotrypsin specifically cleaves peptide bonds at the C-terminal end of bulky hydrophobic or aromatic amino acids (such as tyrosine, tryptophan or phenylalanine). Chymotrypsin Activity Assay kit uses a synthetic fluorogenic substrate, enabling kinetic measurement of chymotrypsin activity in cell and tissue lysates. A chymotrypsin activator cleaves chymotrypsinogen to form active chymotrypsin, which then hydrolyzes the non-fluorescent substrate to release a stable fluorophore (Ex/Em = 380/460 nm). The kit includes a selective chymotrypsin inhibitor that can be used to measure specific chymotrypsin activity in samples containing non-specific proteases and endopeptidases that may also metabolize the substrate. The assay can detect as low as 0.01 mU of Chymotrypsin.