And by cleaving it, we're going to separate it from the rest of the polypeptide. And once we separate it, we want to have a means of separating this amino acid that was cleaved, that was separated and the rest of that polypeptide. And that's why we label it with this phenol ISO thiosyanate molecule. So once again, the bond that we're about to break or that we want to break is this bond. Now, the difficult question is, how do we break this specific peptide bond and at the same time not break any other of these peptide bonds. So we want to create a procedure in which we only somehow break this peptide bond here between this first and second amino acid.