Oxygen Activation in Lipoxygenase Model Reaction Studied with Density Functional Theory

Density Functional Computational studies were performed for the systems containing an iron (III) complex with (cyclam), 1,4-pentadiene and oxygen, where cyclam represents 1,4,8,11-tetraazacyclotetradecane. The calculations have indicated that bond formation between oxygen and carbon atom of the 1,4-pentadiene anion where methylene-proton is removed, occurs in the presence of the Fe III -(cyclam) complex, giving the hydroperoxy derivative of the 1,4-pentadiene. Based on these results it seems quite reasonable to assume that deprotonation of the methylene proton should be a trigger for the peroxidation of the 1,4-pentadiene moiety and the electron transfer reaction between iron(III) atom and the substrate is unnecessary in the lipoxygenases.