Binding Properties of CO, NO, and O2 to P450 Heme: a Density Functional Study

The structural and binding properties of diatomic molecules CO, NO and O2 to P450 heme were investigated in two different models (labeled as M1 and M2) using density functional method at the B3LYP/6-31G(d) level. The effects of the serine residue near diatomic molecules XO were considered in the model M2. The results show that the serine residue near the heme enforced the binding of XO to heme. Frequency analysis indicates that the stretching vibrational frequency decreased as CO, NO, and O2 complex with heme.