Studies On Quantitative Structure-Activity Relationship Of Zinc(?) Chelate Peptides From Rapeseeds

Zinc(?)chelating peptide(ZCP)can react with Zn²⁺,which is regarded as a kind of novel carrier for microelement supplements and is also one of the research hotspots.However,the structure-activity relationship of Zn(?)chelating peptides still remains unclear.Therefore,this study investigated the relationship between the structure and activity of Zn(?)chelating peptides by quantitative structure-activity relationship(QSAR)method.A high active zinc(?)chelating peptide,ASH,was isolated and purified from the rapeseed protein hydrolysates in previous research.Sequence replacement was performed to synthesise 88 tripeptides and tetrapeptides and their relative chelation rates were determined.18 different amino acid descriptors were collected,meanwhile a zinc(?)chelating peptide database and a amino acid descriptor database were established.61 tripeptides in the Zn(?)chelating peptide database were characterized by 18different amino acid descriptors.The partial least square method was used for regression analysis to establish a quantitative structure-activity relationship model.The model established by the amino acid descriptors Z,VHSE,SZOTT,FASGAIand HESH conformed to the requirements,and the model established by FASGAI descriptor was the best(R²=0.8580,Q²=0.6479,R²_ext=0.8420).According to the results of the QSAR model based on descriptor FASGAI,the position of N1 in the tripeptide sequences had the greatest effect on the activity(N₁>N₂>C₁),among which the amino acid residues with lower stericity may increase the activity of the zinc(?)chelating peptide.For the mixed databases,polypeptides of different lengths were processed by two-terminal position numbering method,and 18 kinds of amino acid descriptors were used for the characterization.Moreover,the partial least square method was used for regression analysis.Among the 18 amino acid descriptors,8 of them were confirmed:Z,VSGE,VHSE,SZOTT,TEN,FASGAI,HESH,and ST,respectively.Comparison showed that the model established by FASGAI was the stablest(R²=0.8664,Q²=0.7595,R²_ext=0.8420).The VIP value of C₃ was the highest,indicating that the C₃ site in the sequence had the greatest impact on the activity,in which the attribute contribution was bulky propertie>composition characteristics>local flexibility,and it was concluded that C₃ and N₃ were the sites that mainly affect the activity of zinc(?)chelating peptides in the polypeptide sequences.While the relatively lower stericity may help to increase the activity.Trypsin,pepsin,chymotrypsin and proteinase K were used as hydrolytic enzymes to obtain 113 polypeptides from the virtual hydrolysis of rapeseed-derived protein sequences.Tripeptides and tetrapeptides were selected.The regression equations were used to calculate the prediction values and 9 samples were selected(GCCT,SCGT,CGV,PGCA,DGE,GDT,SGN,CSGV,DGQV).The actually measured activity values and predicted activity values among the samples showed good fitting degree,except for samples DGE and SGN.The validation model had strong predictive power and can be used for rapid screening of zinc-derived chelating peptides and other food-derived zinc(?)chelating peptides.