The Study On Glucose Receptors Based On Cyclic Peptides Structure

Glucose is the most important dietary saccharide source of energy from natural carbohydrate.Disorders of glucose metabolism can lead to a series of health problems,such as hyperglycemia and hypoglycemia.In clinical or healthcare perspective,the measurement and control of glucose level in blood is of particular importance for diabetic patients to regularly monitor the concentrations and make fast and accurate determination of glucose levels.There have been many existing methods to measure the concentration of glucose including electrochemical and optical approaches,but these methods of detection have a series of limitations.Therefore,glucose assay is of great scientific significance in clinical diagnostics and bioprocess monitoring and to design new glucose receptor is necessary for development of more sensitive,selective and robust glucose detection techniques.Oligopeptides have been designed to mimic protein-protein interactions and the epitopes of protein interfaces in living systems,and found applications in drug development,peptide libraries,and biosensors.Herein,a series of cyclic peptides(CPs)glucose receptor were designed to mimic the binding sites of glucose binding protein(GBP)and CPs' sequence contained amino acid sites Asp,Asn,His,Asp,Arg,which constituted the first layer interactions of GBP.The properties of these CPs used as a glucose receptor or substitute for the GBP were studied by using quartz crystal microbalance(QCM)technique.It was found that CPs can be formed a self-assembled monolayer at Au quartz electrode surface and the monolayer's properties was characterized by using cyclic voltammetry,electrochemical impedance spectroscopy and atomic force microscopy.The CPs' binding affinity to saccharide(i.e.,galactose,fructose,lactose,sucrose,and maltose)was investigated and the CPs' sensitivity and selectivity toward glucose were found to be dependent upon the configuration,amino acids sequence of the CPs.The cyclic unit with a cyclo[-CNDNHCRDNDC-]sequence gave the highest selectivity and sensitivity for glucose sensing,the binding constant Ka was 8.14 × 107 M-1.The developed method shows a good recoveries ranging from 82%to 86%in the determination of glucose in human serum samples.This work suggested that a synthetic peptide bearing a particular functional sequence could be applied for developing a new generation of glucose receptor and would find huge application in biological,life science and clinical diagnostics field.