Isolation,purification and identification of antioxidant peptides from Antarctic krill
Antarctic krill is a large number of shrimps living in the Antarctic waters,which is a high-quality protein source and also known as an important reserve protein bank for humans.Antarctic krill contains a large number of active substances such as peptides.In this study,the defatted powder of Antarctic krill was enzymolized to prepare the active small molecule peptides.In order to prepare the krill peptide hydrolysate with strong antioxidant activity,the hydrolysate was purified by ultrafiltration and Sephadex G-15 gel column.Its antioxidant activity was measured.Liquid chromatography-mass spectrometry(LC-MS)was used to analyze and identify the three components separated by Sephadex G-15,and their peptide structures and activities were analyzed to obtain a highly purified and effective antioxidant peptide.The experimental results showed that the antioxidant peptides prepared from defatted Antarctic krill powder had good scavenging abilities of DPPH,superoxide anion and hydroxyl radical.After initial ultrafiltration separation,three components were obtained:＞10 Ku,5-10 Ku,＜5 Ku.The antioxidant activity of each component was determined after freeze-drying,and it was found that the component with a molecular weight＜5 Ku had higher antioxidant activity than the other components.The DPPH,hydroxyl radical,superoxide anion scavenging rates and iron ion chelating ability of the component with a molecular weight＜5 Ku were 84.74％,91.36％,61.92％and 57.95％(protein concentration 10 mg·mL-1).The＜5 Ku component obtained by ultrafiltration was further separated and purified by Sephadex G-15 gel-filtration chromatography to obtain three components:F1,F2,F3,which were enriched and freeze-dried.The DPPH,superoxide anion and hydroxyl radical scavenging effects of each component were determined.The results showed that the overall antioxidant effect was improved compared with the enzymolysis solution.The three components separated and enriched by dextran gel column were detected,and the structure was identified by liquid mass spectrometer.The results showed that a total of 134 peptides were identified from three isolated samples.The length of the peptide chain was 6-40 amino acids,among which there were 25 active peptides composed of 7 amino acids.It could be seen that the enzymatic hydrolysis effect was very good,and the protease could be decomposed into small molecular peptides.The components of antioxidant peptides of Antarctic krill were analyzed with software to obtain secondary mass spectrometry data,and most of the peptides were found to be highly active and non-toxic.It is speculated that peptide chains LPGAIP,GPIALPE,APGELPY,RDWPEGR,GIPPAP and VDLPGW have antioxidant effects.These peptides can be synthesized artificially and provide reference value for the development of Antarctic krill products and antioxidant health food in the future.
Antarctic krillantioxidant peptideseparation and purificationliquid chromatography-mass spectrometry
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