And the S One pocket in China trypsin is basically that region to which that side chain group will actually move into. And if we examine the shape and structure of the S One pocket, we're going to find that it's relatively long, so relatively deep and mostly hydrophobic, so non polar. And because of that structure of the S one pocket, only those amino acids that contain side chain groups that are long, nonpolar, do not have any charges, will actually be able to fit into that pocket, into the active side, without creating too much electric repulsion. 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.