Study On Separation And Purification,Physicochemical Properties Of Abalone Viscera Collagen ACE Inhibitory Peptide

Abalone is a marine biology rich in nutrient substance.However,during abalone processing,a great amount of abalone viscera(20?30%of its weight)has been abandoned or turned into low-price products,which led to a waste of resource and environmental pollution.Connective tissue of abalone viscera belongs to processing waste rich in protein(12.54%),but low fat(2.04%).And the content of its initial collagen was 33.77%.In addition,proline amino acids,aromatic amino acids,hydrophobic amino acids and alkaline amino acids accounted for 5.47%,4.89%,32.46%and 12.88%in total amino acids,respectively.These amino acids were in conformity with ACE inhibitory peptide.Therefore,Connective tissue of abalone viscera was a kind of good raw material preparing collagen ACE inhibitory peptide.At earlier age,our group has extracted collagen peptide from connective tissue of abalone viscera,and verified its physiological activity,such as antioxidant activity and antihypertensive activity.In this study,abalone viscera collagen ACE inhibitory peptides were isolated and purified for further analysis of its structure and nature.First of all,ultrafiltration technology was used to separate abalone viscera collagen ACE inhibitory peptides.Meanwhile,the influence of material liquid concentration,operating pressure,operating temperature and pH on separation effect was studied.Two collagen peptides with different molecular weight(Mr>3000Da and Mr<3000Da)were obtained and their activity were tested.The results showed that the optimal separation conditions were:peptide concentration of 2%,operating pressure of 0.05MPa,operating temperature of 25? and pH value of 7.The ACE inhibitory rate of peptide(Mr<3000Da)was 78.57%,11.45%higher than peptides' activity(Mr>3000Da).Thus,ACE inhibitory activity of peptides with small molecular weight was better.Secondly,only one composition was fractionated by single or gradient elution from DEAE-52 cellulose anion exchange chromatography.The yield of peptide by gradient elution was 82.7%and ACE inhibitory rate of the peptide was 81.23%.Then,the peptide was eluted by distilled water from Sephadex G-25 molecular sieve column and the elution curve was single symmetrical peak.ACE inhibitory rate of the peptide was 82.12%.Accordingly,the nature of peptide after ultrafiltration had little difference.Thirdly,it showed that the structure difference of the peptides before and after ultrafiltration appeared in the fingerprint area.After ion column,only beta folding structure was found in the secondary structure of peptide.So we can conclude that beta folding structure played an important role in ACE inhibitory activity of abalone viscera collagen ACE inhibitory peptides.Finally,physicochemical properties of abalone viscera collagen ACE inhibitory peptides were studied.And enzymatic hydrolysis resistance was tested by simulating gastrointestinal environment in vitro.The results showed that pH had no effect on solubility of abalone viscera collagen ACE inhibitory peptides.The solubility was around 85%within 2 to 10 of pH value.ACE inhibitory rate dropped sharply when NaCl concentration was beyond 0.8mol/L.Abalone viscera collagen ACE inhibitory peptides was stable in neutral and acidic environment.Pepsin and trypsin had little effect on activity of abalone viscera collagen ACE inhibitory peptides.Therefore,abalone viscera collagen ACE inhibitory peptide is a good edible polypeptide.