Theoretical Investigation On The Mechanism Of Metalloproteinase Bionic Catalytic Reaction

Proteins are biological macromolecules with amino acids as the basic unit,and proteins that bind to metal ions in an organism are metal proteins.Many life metals represent their biological functions in the form of metal proteins or metal enzymes.Protease,known as the catalyst in the life body,is produced by cells and has a highly selective and catalytic activity of a class of special proteins.The composition of protease can be divided into pure protein and binding protein.Among them,the enzyme protein in binding protein is the protein part and the auxiliary factor is the non-protein part.The two parts combine to form a complete enzyme,and only the complete enzyme has catalytic activity.Non-heme iron enzyme is a kind of important metalloproteinases,which is widely used in chemical,biological,environmental and medical fields.Although some of the reaction products can be determined by experiments,the detailed reaction mechanism of non-heme iron enzyme and the reaction intermediates,transition states of different reaction substrates are not available only through experimental methods.Therefore,this paper mainly uses density functional theory to study three kinds of representative non-heme iron metalloproteinases: Gentian-1,2-dioxygenase,Dioxygenase Asq J and Alk B enzymes.The first,Gentisate-1,2-dioxygenase?GDO?,a nonheme iron enzyme in the cupin superfamily,catalyzes gentisic acid to form maleylpyruvic acid in the microbial aerobic degradation of aromatic compounds.Reaction requires the participation of oxygen molecules,the substrate with the participation of oxygen form pyrolysis products.The oxidative decomposition of aromatic compound gentisic acid catalyzed by GDO was studied on the basis of density functional theory.The results show that the conjugated compound iron complexes with oxygen to form iron superoxide radicals,the final formation of high-valent FeIV-oxo species as a key step.Based on the theoretical calculation,the optimal spatial configuration parameters,the frontier molecular orbital and the total energy are obtained.The second,Dioxygenase Asq J is involved in two different oxidative reactions of viridicatin biosynthesis reaction: the desaturation reaction and the epoxidation reaction.Dioxygen-activating non-heme Fe2+/?-ketoglutarate-dependent oxygenases participate in a vast array of biologically important and energetically demanding reactions,which produce CO₂ and succinate acid with an enzyme-mediated binding of ?-ketoglutarate??-KG?,and are likely involves a high-valent FeIV-oxo species as the key intermediate.The One-Pot multistep quinolone antibiotic biosynthesis of 4-methoxyquinolone antibacterial drug was studied with the Fe²⁺/?-ketoglutarate-dependent dioxygenase Asq J by density functional theory.The results show that the reactions include high-priced iron oxide,desaturation,epoxidation and rearrangement reaction.Among them,no coordination metal is involved in the last step reaction process.The optimal space configuration parameters,the frontier molecular orbital and total energy of the compound were obtained by optimization calculation.The third,Alk B enzyme belongs to non-heme Fe²⁺/?-ketoglutarate-dependent oxygenases,which is activated by oxidant to generate FeIV-oxo intermediate,and then various oxidation reactions.The Alk B family can directly remove the partial DNA base damage by using the non-hemo with the ?-ketoglutarate.The mechanism of Al KB enzyme repairing DNA alkylation injury was studied by density functional theory.The results show that the reaction involves formation of two high valent iron oxides,hydrogen proton transfer and demethylation.In addition,geometric parameters of optimal configuration,frontier molecular orbital and energy were calculated and analyzed to obtain the optimal reaction pathway.