And when it collapses, what happens is the lone pair of electrons on the oxygen forms a pi bond with this carbon and that breaks off this relatively weak nitrogen bond. And so when this bond breaks off, the electrons on those bond on that bond basically move on and grab this H atom because by grabbing the H atom away from this histidine, this loses that positive charge and becomes more stable. And that can be seen in this diagram here. So after step two, after this tetrahedral intermediate collapses, that essentially oscillates this serine residue. So this acyl group is now attached onto this oxygen and this amide has been formed. And the amide takes away this H atom from the nitrogen found on this side chain of histidine 57.