And so, because it's so unstable, it doesn't exist for a very long time. And what happens is, again, the two electrons on the oxygen basically form a pi bond between the carbon and this oxygen. And now what happens is this bond here showed in green that we basically formed in this step is now broken. And when this bond breaks, the two electrons that exist in that Sigma bond now basically move on to this H atom and take away that H atom. And again, the reason we want to take away that H atom is because we want to remove this positive charge that exists on the ring of this Histidine 57 side chain. And so, in the next step, we basically reform that alcohol group found on the serine, we remove that H atom that was on the nitrogen.