Isolation And Purification Antibacterial Peptides From Camel And Cow Milk Whey Proteins And Comparative Analysis Its Antibacterial Activity

Camel milk has rich nutritional value and high medicinal value,its whey protein is rich in protective protein,and contains high activity antibacterial factors.In this study,camel milk and milk whey protein were used as raw materials to study the hydrolysis process of pepsin and trypsin,and the optimum conditions of hydrolysis were determined.The peptides obtained by enzyme hydrolysis were separated by ultrafiltration technique,and the whey protein peptides with antibacterial activity were obtained by dextran gel chromatography.The main experimental results of this paper are as follows:1.Taking the bacteriostatic rate as the evaluation index,the preparation of bacteriostatic peptide by pepsin and trypsin was optimized by response surface method.Obtaining the optimal enzymatic hydrolysis of camel milk whey protein parameters:enzymatic hydrolysis temperature is 40.16?,enzymatic hydrolysis pH is 3.00,enzymatic hydrolysis time is 5.36 h,enzymatic hydrolysis substrate concentration is 4%,enzyme to substrate concentration ratio The 1:100,the inhibition rate was 84.03%;the optimal enzymatic hydrolysis of bovine milk whey protein was obtained:the enzymatic hydrolysis temperature was 39.24?,the enzymatic hydrolysis pH was 3.00,and the enzymatic hydrolysis time was 4.89 h.The concentration of the substance was 4%,the ratio of enzyme to substrate concentration was 1:100,and the inhibition rate was 82.11%.The optimal enzymatic hydrolysis of camel milk whey protein was obtained:the enzymatic hydrolysis temperature was 45.36?,and the enzymatic hydrolysis pH was 8.58,the enzymatic hydrolysis time was 3.57 h,the enzymatic hydrolysis substrate concentration was 4%,the enzyme to substrate concentration ratio was 1:100,and the inhibition rate was 73.01%;the optimal enzymatic hydrolysis of bovine milk whey protein was obtained:The enzymatic hydrolysis temperature was 40.96?,the enzymatic hydrolysis pH was 7.78,the enzymatic hydrolysis time was 3.93 h,the enzymatic hydrolysis substrate concentration was 4%,the enzyme to substrate concentration ratio was 1:100,and the inhibition rate was 73.56%.The degree of hydrolysis was identified by electrophoresis,and it was found that camel milk was more easily hydrolyzed by protease than cow's milk to prove that it was more digestible and absorbable.2.The enzymatic hydrolysate was subjected to ultrafiltration and purification by glucan gel chromatography to obtain components with strong antibacterial activity,which were pepsin enzymatically catalyzed camel milk and milk whey protein antibacterial peptide component G-25-2 and G-25-2' and trypsin enzymatically catalyzed camel milk and milk whey protein antibacterial peptide components G-25-2 and G-25-1'.3.The results of amino acid analysis indicated that the content of hydrophobic amino acids(65.76%)and basic amino acids(32.8%)in the G-25-2 component of camel lipase was higher than that of milk G-25-2'.(51.77%and 31.77%,respectively);the content of basic amino acids(28.13%)in the G-25-2 component of camel milk trypsin is higher than that of milk G-25-1'(25.07%),but The content of its hydrophobic amino acid(51.29%)is lower than that of the milk G-25-1' component(57.69%).In this experiment,the content of proline in the antibacterial peptide component of Camelin G-25-2(32.34%)was significantly higher than that in other antimicrobial peptide components(p<0.05).It further demonstrates that the antibacterial activity of the camel papain antimicrobial peptide is stronger than that of the milk emulsion antimicrobial peptide.4.Molecular weight analysis showed that the molecular weight range of the pepsin-encapsulated camel milk and milk antibacterial peptide components G-25-2 and G-25-2' were 651.35?673.33 Da and 516.81?1070.6 Da,respectively;trypsinase The molecular weight ranges of the antibacterial peptide components G-25-2 and G-25-1' of the camel milk and milk were 508.24?1438.77 Da and 533.29?1665.66 Da,respectively.5.Study the stability and bacteriostatic properties of each component.Escherichia coli and Staphylococcus aureus were used as indicator bacteria to determine the minimum inhibitory concentration and growth curve inhibition of each component,and Escherichia coli was used as indicator bacteria to study the antibacterial activity of high temperature and different pH Impact.The results showed that the components were stable to high temperature and had obvious antibacterial effect under acidic conditions.Under neutral conditions,the antibacterial effect was weak,while under alkaline conditions,the antibacterial effect decreased drastically.