Study On The Active Peptides From Oyster By Enzymolysis

The Oyster have been figured into the drug and food list by the ministry of health in China,and have good nutrition and health care effect.Though the oysters resource in our country is very rich,the product processing form is too simplex,and the main is dry products.In this paper,oysters were used as raw material,and oyster peptides were prepared by protease enzymolysis.We used the glucan gel column chromatography to purify and separate the antioxidant peptides components.And then these amino acids sequences of antioxidant peptides were analysed by HPLC and MALDI TOF-MS/MS.And also their antioxidant activity by measuring the activity of scavenging free radicals in vitro and cell experiments were evaluated,and it provided the basis for oysters's high value development.The main results were as follows:We measured the clearance rate of DPPH free radical,hydroxyl free radical,superoxide anion free radical of the hydrolysates?their degree of hydrolysis and the distribution of molecular weight,analysed the hydrolysis effect of oyster protein by 6 kinds of protease and antioxidant activity of the hydrolysates,and choosed the neutrase as the protease to hydrolyze oyster protein.On the basis of single factor experiment,the conditions of oyster protein hydrolysis by neutrase were optimized by the response surface design experiment.Eventually,the appropriate hydrolysis conditions were determined.The hydrolysis temperature was 48?,the pH of material liquid was 7.6,the substrate concentration was 1.04%,the enzyme amount was 2000 U/g,and the enzymolysis time was 12 hours.The oyster protein peptides obtained through enzymolysis were separated and purified by Sephadex G-25 gel column.NA?NB?NC and ND four main components were got and the activity of scavenging DPPH free radicals of NA and NB components is significantly higher than NC and ND components.The amino acid sequence of these four components were analysed by HPLC and MALDI TOF-MS/MS.And we finally got seven purposed peptides.Their amino acid sequences are as follows:LDLYLS?812 Da??VLSGGTT?741 Da??REYKQ?723.8 Da??LLRALTK?814.8 Da??RRKRAAG?814.8 Da??AAELQ?531.6 Da??SAFW?509.9 Da?.The activity of scavenging free radicals showed that the oyster protein peptides N and NA?NB components had good activity of scavenging DPPH free radicals,and the NA components was the strongest.The scavenging free radicals rate is 67.1±0.61%.The oyster protein peptides also showed good activity of scavenging hydroxyl free radical and superoxide free radicals.The NA components had the strongest activity of scavenging hydroxyl free radical?48.5±0.57%?,but the least activity of scavenging hydroxyl free radical.The NB components had high activity of scavenging hydroxyl free radical,but very low activity of scavenging hydroxyl free radical.We analysed oyster protein peptides and components NA?NB's influence on LO2 cell viability?the leakage amount of LDH?the level of MDA?the GSH-Px in LO2 cell that was damaged by H₂O₂and the activity level of SOD,and it is concluded that oyster protein peptides?NA and NB components played a role in protecting LO2 cell when LO2 cell were damaged by H₂O₂.