Study On Acetylcholinesterase Mimics Based On Peptided And Cotton Fiber Composites

The vast majority of natural enzymes are proteins that have the function of biological catalysis,which take part in almost all of the cellular activities.Enzymes are extremely efficient at catalyzing a variety of reactions with high substrate specificity,activities,and yields nuder mild reaction condition.They have successfully used for many different tagets in various fields including biosensing,agrochemical production,pharmaceutical engineering,food industry.However,natural enzymes have intrinsic drawbacks for connercial applications,including their low stability(denaturation and inactivation),sensitivity of catalytic activity to environmental conditions,difficulties in prepare,purity,recovery and recycling,high cost of product.The appearence of minic enzyme overcomes the shortcomings of natural enzymes.As a replacement of natural enzyme,mimic enzyme is effective and there is a broader range of application.Hydrolytic enzymes are the general term for a class of enzymes that catalyze the hydrolysis reaction.Serine hydrolase was chosen as an object of enzyme mimic system,using Acetylthiochromoacetate as the reaction substrate.The influencing factors such as pH value,temperature,substrate concentration,reusability,stabilization and inhibitor were investigated by control variate method.Natural hydrolytic enzymes generally contain catalytic groups(the catalytic triad)that directly involve in the catalytic process and connecting groups that involve in substrate binding.Therefore,the optimal conditions for the mimetic enzyme were obtained by simulating the hydrolase by connecting the peptide catalysis center(serine,glutamic acid,histidine)and the tryptophan of binding site to the cotton fiber.In this experiment,first,The cotton fiber was oxidized and the small peptide was connected with the cotton fiber by reaction of aldehyde groups with amino groups,and obtained the best conditions is the oxidant concentration in the 20 g/L,temperature is 55?,reaction time was 1h.By calculating the aldehydized efficiency is 1.5%.And then through the aldehyde-ammonia condensation reaction,the peptide was connected with cotton fiber,getting the connection efficiency is 55%.The optimum catalytic conditions for the simulated enzyme were the highest catalytic efficiency at the concentration of acetylchiocholine iodide 0.683 mM,pH = 9.0 and temperature of 75 ?.The Michaelis-Menten constant of the enzyme was obtained from Km = 3.39 mM.This work showed that a well-designed combination of cotton fiber and short peptides containing active sites can mimic a natural enzyme.This study is expected to provide some guidance and help for the study of artificial enzyme.