So although Trypsin elastics use the same mechanism, so covalent catalysis and acid based catalysis, which we spoke about in the previous lecture, they differ in their specificity. And that has to do to the fact that there is a slight structural difference in the s one pocket in Trypsin as well as elastics. And let's see what these differences are and what they result in. So let's begin with trypsin. So Trypsin catalyzes the cleavage of peptide bonds on the carboxyl end of Lysine and Arginine. And if you recall, Lysine and Arginine both contain positive charges on their sidechain groups.