 The dephosphorylation of the pTyr substrate occurs in the first step, while the enzyme intermediates are broken down during the second step.During the first step, there is a nucleophilic attack at the phosphocenter by the reduced Cys215 residue, followed by subsequent protonation by Asp181 to yield the neutral tyrosine phenol.The active enzyme is regenerated after the thiophosphate intermediate is hydrolyzed, which is facilitated by the hydrogen bonding interactions of Gln262 and Asp181 that help to position in the water molecule at the desired site of nucleophillic attack.