| In recent years,food-borned antioxidant peptides has become one of the attractive thesis’s for its unique properties of secure source,rich variety,high activity and stability and easily absorbed.Separating antioxidant peptides from animals,plants and microbial protein by hydrolysis have been reported in a large number of literatures at home and abroad.However,the research on structure-activity relationship of antioxidant peptides is still in a initial stage,and mainly concentrated in the analysis on composition of amino acid and speculation on conformation of peptide.synthetic or transformation of antioxidant peptide lacks adequate theoretical basis,some aspects even exists blind spots.This paper takes 20 amino acids as the main research object,compares the results of different groups/methods:HF/6-31g（d）,B3LYP/6-31,B3LYP/6-311+G（d,p）by quantum chemical calculation,selects the group which is suitable for calculation for providing directions to further study on the sequence of the macromolecular peptide by combining the computing time with accuracy.On the basis of the molecular configuration of amino acid simulated by quantum chemistry and the parameters of structure/energy by calculation,the possible active site can be speculated for preliminarily clarifying the possible antioxidative mechanism of the natural amino acid and providing theory basis for applying methodology and the antioxidative mechanism to the food-borned antioxidative dipeptides,tripeptide and polypeptides.The antioxidant activity of 11 foodborne antioxidant peptides reported in home and abroad is researched by the study method of quantitative structure-activity relationship（QSAR）.They are REW and RVF separated from wheat germ by our research group in the preparation period,FM and VHHH got from wheat germ,AQIPQQ got from wheat gluten,TTYY got from soybean protein,NRYHE got from chickpea protein,VIPAGYP and its analogues（VIPAGY,PAGYP and PAGY）got fromβ-conglycinin in soybean,including 11 foodborne antioxidant peptides selected from different plants and different peptide lengths from 2 to 7.Structure parameters of 11 antioxidant peptides could be obtained by the group/method introduced by the chapter two.At the same time,activity parameters could be obtained by the experiments on measuring the scavenging activity of O2-·and·OH.By using the parameters,the model of quantitative structure-activity relationship（QSAR）could be built by method of multivariate linear regression（MLR）.Besides,in order to demonstrate the validity of model,the leave one out cross（LOO）validation method is used to examine the model.The results show that the O2-·model has higher prediction ability and the energy related with the ability of supplying electron(EHOMO)and the bond length of active site(L（X-H）)has great influence on the activity of antioxidant peptides,which could provide theoretical guidance for the follow-up study on screening and synthesizing of high activity antioxidant peptide.And then,the quantum chemistry structure parameters of the designed antioxidant peptides were calculated,and based on the scavenging model of O2-·and·OH,which introduced by the chapter two,the antioxidant activity was predicted.The predicting results show that RDW and KEW（Based on REW design）,RVW and RVY（Based on RVF design）have higher antioxidant activity,and the predicting results has been verified by the solid-phase synthesis experiment and the antioxidant activity experiment.Meanwhile,the mechanism of antioxidant activity of REW and RVF get further clarified through the analysis on its quantum chemical parameters. |
