Chemical Physics Letters, Vol.428, No.1-3, 152-156, 2006
On the formation of Horseradish Peroxidase Compound I at high pH: New insights from ab initio molecular dynamics
Compound I formation at neutral or basic pH, starting from ferric peroxidase-peroxide complex has been described, for the first time, by ab initio, molecular dynamics on doublet surface. Proton transfer involving distal residues occurs efficiently in a stepwise mechanism in which the O-O bond is broken. An energy barrier of 4.8 kcal/mol is found to obtain the final products when the Fe-III[O-OH]((-)) complex is formed on the doublet surface. In the final part of the reaction, just before Compound I formation, a spin crossing between doublet and quartet magnetic surfaces is observed in our model system. (c) 2006 Elsevier B.V. All rights reserved.