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. And so now we have this slight interaction between the nitrogen and the hydrogen and we still have the interaction between the oxygen and this hydrogen. So this oscillates the therine and forms an amide molecule that deprotonates the histidine nitrogen shown here. And once we form this amide product, in the next step, the amide basically moves away.