So amino acids such as methionine, phenyl, aline, tyrosine and Tryptophan. So once again, it's the catalytic triad in the active side. It's the presence of these three individual amino acids that give climate Trypsin its catalytic power, the ability to actually catalyze the cleavage of those peptide bonds. But it's this long and narrow shape and the fact that it's mostly hydrophobic, it's the shape of the S one pocket that actually gives chymetrypsin its specific nature, its specificity to Cleave only on the carboxyl end of specific side chain groups. Now, as we discussed in our study of proteases, we basically said there are many different types of proteases that exist inside our body and inside nature. Now, so far, we focused on Serene proteases and we use Chimetrypsin as the prototypical seren protease.