Study On Hydrolase Mimics Based On Peptided And Mesoporous Silica Composites

In order to overcome some inherent defects of natural enzymes,a mimic of natural enzymes was synthesized by Chemical methods.Serine hydrolytic enzymes,one of the six types of enzymes,as a mimic object in this experiment.The p-nitrophenol acetate was used as the catalyst substrate for the mimic enzyme.The effect of the different temperature,concentration of substrate,pH and concentration of the composites on the catalytic activity was investigated by the control variable method.Natural hydrolytic enzyme active center typically contains Catalytic groups(catalytic triad(S,H,E/D))and the group that bines with the substrate that involved in the catalytic process directly,and these amino acid residues are close in space by the coiling of the peptides.However,some researches have also shown that the self-assembly of small peptides with a single catalytic group of histidine,one of the three catalytic groups of hydrolytic enzymes,can also have catalytic activityComparing the catalytic activity of different composites,the optimal enzyme mimic was obtained and the reaction condition with the best catalytic effect were determined by using a small peptide consisting of only catalytic group histidine(H)and binding group tryptophan(W)on the surface of mesoporous silicon nanoparticles to mimic hydrolase in this study.First,mesoporous silicon was synthesized and aminized,then the carboxyl group of the peptides were used to bind the amino groups on the surface of mesoporous silicon nanoparticles to form amide bond by EDC/NHS method,and the efficiency of the connection was optimized.Then,obtained the highest bind efficiency is 64.3%in the condition of the concentration of EDC is 0.03mol/L,the pH of system is 6.5,the ratio of EDC:NHS:Peptide-COOH = 30:10:1 and reaction time is 24 hours.Through the determination of the catalytic activity of the composite,it is concluded that the optimal simulation object is a composite material(H/W)2:1 LKLKLKLKL-MSN.Under the conditions of pH is 8.0,the temperature of 55 ? and the composite mimic is completely saturated when the substrate concentration is 2.61 mmol/L.According to the all experimental results,when only one catalytic group H is contained,it also has certain catalytic effect.The existence of the binding group W plays an effective role in promoting the reaction by binding the substrate effectively.And the Michaelis constant measured by the Michaelis-Menten equation is 4.01 mM.This study shows that the peptide with active sites combine with mesoporous silicon can effectively mimic the catalytic activity of natural enzymes.