So it removes a dipeptide from this region to basically remove two amino acids. That's why we go from 15 to 13 and we also cleave in this section and we remove a dipeptide. And so that's why we have two amino acids missing in this section. And so once we form these three individual chains these three individual chains are held together by disulfide bonds. And now the active side takes the proper confirmation and the oxyanine hole that is used to stabilize that tetrahedral intermediate takes on that perfect form so that once the active side is formed it can actually fit that substrate intermediate. And once the reaction takes place the tetrahedral intermediate can be stabilized by that fully formed oxyanion hole.