And so the only bonds that Trypson will be able to cleave are this bond and this bond here. So at the carboxyl end of Lysine and arginine, so we see that a very tiny variation in the structure of the s one pocket in Trypsin gives Trypsin a different specificity than that of chimetrypsin. And finally, let's move on to elastics. So, if we examine the s one pocket of Elastanes, we'll see the presence of two additional Valene and valine, if you recall, are these small or valine molecules, have these small, relatively small hydrophobic chains. And notice where these two valleys are positions, they're positioned opposite of each other and they essentially play the role of blocking the majority of the bottom portion of that s one pocket. And so what that means is when the side chain group of the amino acid moves into the s one pocket, it cannot actually occupy this space here because this blocks, as a result of the stair kindle of the hydrophobic properties of these side chain groups.