Theoretical Kinetics and Thermodynamics study peripheral substituenteffects on the hydrolysis of verdoheme

The heme oxygenase enzyme is a free heme protein that binds to heme in the body. Hemeacts as both a substrate and a cofactor in this enzyme. The heme oxygenase enzyme (HO) plays akey role in destroying heme molecules. Studies of the reaction of ۵-oxaporphyrin iron complexes(verdohemes) with peripheral substituent on the heme ring have been undertaken to providemodels and largely unknown for the initial step in hydrolysis of verdohemes. In this work atheoretical kinetics and thermodynamics study of degradation reaction of verdohemes wasperformed, and calculations show that ΔGReaction in hydrolysis of verdohemes non- peripheralsubstituent is more negative than hydrolysis of verdohemes with peripheral substituent. In theother words, hydrolysis of verdohemes with non- peripheral substituent is more energy efficientthan verdohemes with peripheral substituent. The equilibrium constant calculation shows thathydrolysis of verdohemes non- peripheral substituent is much faster than verdohemes withperipheral substituent, which it is due to more convenient nucleophilic attack to cationic ringthan anionic. In order to obtain a better molecular understanding of peripheral substituent effectson the hydrolysis of verdoheme inhibitory role of have been studied using DFT method.

کلیدواژه ها:

Heme oxygenase ، peripheral substituent ، DFT method ، Hydrolysis ، Ring Opening ofVerdohemes.