Study On The Extraction And Purification And Functional Properties Of Muscle Active Peptide In Onchidium Struma

Onchidium struma is a kind of marine organism belonging to Mollusca,Gastropoda, Pulmonata, Stylommatophora, Onchidiidae. Its muscle is rich in proteins and peptides which has a profound developing potential, in order to investigate the features of its muscle proteins and polypeptides, the main conclusions of this study were indicated as following.With Onchidiumstruma as raw material, using trypsase, papaya protease,pepsase, neutrase and alkalase these 5 kinds of protease for enzymolysis with degree of hydrolysis as the reference index, the best two digestion effect enzymes(alkaline protease and trypsin) were chose for the further test, using composite enzymatic hydrolysis by trypsase and alkalase, through odd factor test and response surface method, the optimum conditions of enzymatic hydrolysis are temperature:51℃, pH:10, time:2.2 h, enzyme ratio:1:1, the DH could reach 20.13%. The four single factors(enzymatic hydrolysis temperature,pH, enzymatic hydrolysis time and enzyme ratio) had remarkable influence on the O.struma muscle protein hydrolysis degree as well as the interaction of temperature and pH was significant.Preparing Onchidium struma muscle protein enzymolysis liquid according to the optimum conditions, then the enzymolysis liquid were separated by ultrafiltration tubes with different molecular weight cut(1kD,3kD), DPPH free radical clearance rate had been used as a selection criterion to find out the most active component for further purification, with DPPH free radical scavenging and hydroxyl radical scavenging as index, the highest antioxidant activity peptide component were found out using SP Sephadex C-25 ion exchange chromatography separation and Sephadex G-75 gelfiltration chromatography separation respectively, the components of the molecular weight range were determined by Sephadex G-75. The results showed that three components(OSM1,OSM2 and OSM3) were found out after ultrafiltration, OSM3 suggesting the best antioxidant ability, three fractions were purificated through SP Sephadex C-25 column from OSM3(<1kD), OSM3-2 has the strongest antioxidant ability, continue to use Sephadex G-75 gel column to separate OSM3-2, two components were washed of distilled water and PBS, OSMP1 component had better antioxidant effect, clearance rate was 72.25% and 73.8% respectively, moreover, the formula weight distribution of OSMP1 was 558-1032.Suction force, oil absorption force, emulsification and its stability, foam and its stability and total reducing power of Onchidium struma crude protein and polypeptide under different conditions were compared, the results showed that suction force of its crude protein was obviously higher than that of polypeptide, temperature had little effect on suction force of O.struma, but evident effect on oil absorption force, as the temperature increased, water power dropped, oil absorption force of crude protein was better than that of polypeptide, and as the temperature changes, oil absorption force of crude protein remained unchanged but polypeptide’s oil absorption force began to decline, emulsification and foam of crude protein and polypeptide changed with the change of pH which both reached the lowest point in IEP, there was a certain total reducing power of crude protein and polypeptide, but lower than that of VC, total reducing power of polypeptide were better than that of crude protein.