And to gain a better understanding as to what takes place inside the active sites, we're going to study a specific example of a protease that is found inside our body, namely chimetrypsin. So chimetrypsin is actually a serum protease that is found inside the small intestine, which basically hydrolyzes or catalyzes the hydrolysis, the cleavage of specific peptide bonds. It cleaves on the carboxyl side of relatively large and bulky hydrophobic side chain groups, and this includes methionine, phenylalanine. It also includes tryptophan and tyrosine. So, if we take a look at the following hypothetical polypeptide chain that consists of seven amino acids, we have glycine, methionine, phenylalanine, tyrosine, alanine, tryptophan and glycine. And this is the corresponding threedimensional structure.