So this is basically what it looks like. So we remove these four chains and we form the following active fibrin monomer. So monomer simply means we have a single fibrin molecule in its active form. So Thrombin is a serum protease that uses proteolytic activation to activate fibrinogen. This molecule and the way that it activates it is by cleaving at four different sites on that molecule and by cleaving at these four different sites we basically remove four different peptides. And these four peptides are shown here.