Figure 3.

AM1 PESs for hydroxyl formation from oxyanion tetrahedral intermediate of t-DPPO(1) through different possible mechanisms: (a) nucleophilic attack of a water molecule on the carbonyl carbon atom of Asp333; (b) direct proton transfer from His523 to the negatively charged oxygen atom of epoxide; and (c) proton transfer from His523 to the negatively charged oxygen atom of epoxide through a water molecule and Tyr381; (d) AM1 PES corresponding to the nucleophilic attack of a water molecule and the proton transfer to His523 from hydroxyl intermediate. All distances are in Å and energies in kcal·mol⁻¹.