Investigation of the conversion process of verdoheme Hydroxyl Iron (II) to biliverdin Iron (II): Theoretical study

Heme oxygenase (HO) is an enzyme that breaks down heme and as a result iron is recycled in most organisms, including the human body. This enzyme produces bilirubin, divalent iron, and carbon monoxide. Heme Oxygenase was first described in the late ۱۹۶۰s [۱-۳]. Study of the reaction of the peripheral substituents on the heme ring with verdohemes (۵-oxaporphyrin iron complexes) offers models that are not very well known. In this work, a theoretical study of destruction reaction of verdohemes was carried out and the effect of peripheral substitutions on its hydrolysis process was investigated. Theoretical calculations show that hydrolysis of verdohemes non-peripheral substituent than hydrolysis of verdohemes with a peripheral substituent done faster. On the other hand, hydrolysis of verdohemes non-environmental is a more energy efficient alternative. To better understand this process, theoretical calculations were performed using the DFT method. Calculations of the stability energy of the compounds showed that the higher the intermolecular interactions of hydrogen, the greater the stability of the compound. Also, the highest stability energy is related to compound D, which has more intermolecular interactions from type of the hydrogen bonds.