Study On Catalytically Active Polypeptides Toward Hydrolysis Of Glucoside Compounds

Glycosylation of biomolecules（e.g.,proteins or lipids）plays an important role in inducing functions of biomolecules and is a vital process in the bio-system.In recent years,the removal of glycoside sites on protein amino acid residues and regenerating proteins have also received extensive attention.The deglycosylation process can also prepare or develop new drugs from natural products/compounds.The process of deglycosylation requires enzymatic catalysis to remove the glycosylation completely.However,the poor stability and high price of natural enzymes greatly limit their practical application in industry.Based on the above situation,it is necessary to develop analog enzyme materials with natural enzyme activity,stability and low cost.In this paper,natural glucosidase was constructed based on the design of polypeptides and used to hydrolyze glycosides.The major work of this study is:In this work,eight peptides（PE1,PE2,PE3,PE4,PE5,PE6,PE7,PE8）were designed and synthesized,and the self-assembly characteristics of the peptides and their functions as natural glycosidase were explored.These active peptides contain two functional fragments,one is hydrophobic LHLHLRL,which can form assembling segments after complex with Zn ions;another functional sites of the active peptides are the Glu（E）and Asp（D）amino acids sites.It was found that the designed peptide can effectively hydrolyze glycosides at p H 9 and 37℃.The effects of amino acid sequence,p H value and Zn²⁺on the hydrolysis catalytic activity of glycosides were further investigated.The peptides were characterized by transmission electron microscope,fluorescence spectrum,circular dichroism and X-ray diffraction spectrum,the interaction between polypeptide simulate and glycosides was studied by density functional theory and molecular docking.The results showed that at p H9 and 25℃,it was easier to formβsheet nanofiber structure with PE5 as an example.The catalytic hydrolysis activity of polypeptide mimics varied according to different glycosides,the conversion of substrates was in the order:gastrodin（18.4%±2.9%）>esculin（10.4%±2.9%）>polydatin（9.3%±2.3%）,these results showed that the catalytic activity of polypeptides is not only related to the structure of amyloid protein but also affected by the position and type of amino acid sequence.In addition,p H and metal ions also affect peptide self-assembly and stable structure formation.The interaction force between peptide and substrate was preliminarily explored by density functional theory calculation.Molecular docking studies further show the high catalytic activity is because of the combination of gastrodin and polypeptide has higher ability,and artificial enzyme has strong hydrophobic interaction between molecular docking showed that the photocatalytic activity of glycoside compounds of different size differences results from peptide interaction with the substrate,formation of hydrogen bonds can induce peptide mimetic enzyme hydrolysis has higher catalytic activity.This work provides some ideas for design and analysis structure-activity relationship of glycosidase enzyme mimic based on peptide.These results provide an insight for potential applications in the production of high-efficiency artificial enzymes and provide guidance for the design of self-assembled structural enzymes mimics,including artificial enzymes containing a variety of biological and abiotic metal ions.