Theoretical Investigations On The Effects Of Mutations In Important Residues Of Cytochrome P45021A2 On Its Activity Using Molecular Dynamics Simulation

Cytochrome P450 s are heme-containing monooxygenases and are involved in a series of redox reactions by transferring electrons.P450 s have two main physiological functions in nature,one is the synthesis and degradation of endogenous substances,and the other is the metabolic activation and detoxification of exogenous substances.However,the mutation of P450 usually hinders its normal physiological function,causing some diseases and endangering human health.Cytochrome P450 21A2(CYP21A2)is a member of Cytochrome P450 enzyme family,which is important for the synthesis of sterol hormones.Loss of physiological function of CYP21A2 is associated with an autosomal recessive genetic disease.More than 95% of congenital adrenal hyperplasia(CAH)is caused by CYP21A2 mutations.The CYP21A2 mutation will reduce the activity of the enzyme,hinder the synthesis of cortisol,and increase the level of adrenal cortical hormone in the body,leading to congenital adrenal hyperplasia.Therefore,it is of great significance to know the relationship between CYP21A2 mutations and the enzyme's structure and function.In this thesis,we have focused on the effects of several important residue mutations(L108R,G292 C,G292S,G293 D,and T296N)at the active sites of CYP21A2 on enzyme activity.These mutations are usually associated with the most severe clinical phenotypes of CAH.In this work,molecular dynamics simulation and MM-PB/SA binding free energy calculation were carried out for the complexes of wild-type and mutant-type binding substrate.Based on our results,we summarized several reasons that mutations affect the structural characteristics and substrate binding of CYP21A2,which lead to the enzyme activity decrease.1)Mutations destroy the hydrogen bond between the key residue and the substrate,affecting the substrate binding;2)Mutations change the charge environment of the residue,resulting in local conformational changes of CYP21A2;3)Mutations enhance the steric hindrance effect and affect the substrate binding.In addition,our work gives a wonderful explanation of the phenomenon that though the substrate binding ability increase,the reaction activity decreases in T296 N.The present study provides detailed atomistic insights into the structure-function relationships of CYP21A2,which could contribute to understanding about CAH and provide theoretical basis for prediction and treatment of this disease.