We have glycine this one. We have Arginine this one and we have glycine, this one. Now, the only ones that contain positive charges are these two amino acids. And only these amino acids will be able to actually fit into the pocket of Trypsin, and at the end will be able to actually interact in a stabilizing manner. So the positive charges of these two side chain groups will interact with the negative charges of this aspartate 189 and that will create a stabilizing effect, it will neutralize the net charge in that space and that will create a very stable effect. So at the bottom of the active cytotrypsin is an aspartate residue and the negative charge of the aspartate side chain group will stabilize those amino acids that contain side chain groups with positive charges, namely the Lysine and the arginine.