Enzymolysis Technology Optimization Of Active Peptides From Spirulina Protein And Identification Of Antioxidant Peptides From Spirulina Hydrolysates

Bioactive peptides, made up of amino acids, were a kind of compounds with biological activity. Bioactive peptides generally came from plant protein or animal protein. In China, high quality protein resources were becoming less and less. A growing number of bioactive peptides were being identified in different industry. Some of these peptides had been shown to possess immunomodulatory, antimicrobial, antithrombotic, growth-stimulating or antihypertensive properties. This topic mainly with Spirulina as a medium of highly active peptides of enzymatic hydrolysis, utritional components of hydrolysis product and purification and identification of antioxidant peptide from Spirulina hydrolysates were studied, the main results are as follows:(1) The preparation of highly active peptides from Spirulina by the enzyme K was optimized, the optimum hydrolysis conditions were as follows: the ratio of material to water 1:8, enzyme dosage 700 U/g, hydrolysis temperature 55℃, p H 8.5, hydrolysis time 3 h. Under the optimal conditions, the yield of peptides was 43.31%, the yield of amino acids was 11.82%, and enzymolysis liquid were oligopeptide mixture which mainly composed of 2~7 amino acid residues.(2) According to the optimum hydrolysis conditions,the products were analyzed after enlarge experiment. The hydrolysates contained protein 66.55% and peptides 27.35%. The component proportion of molecular weight greater than 350 KDa in raw materials accounts for 69.16%, after enzymatic hydrolysis it was reduced to 12.99%; the component proportion of molecular weight less than 1 KDa in raw materials accounts for 28.33%, after enzymatic hydrolysis it was rose to 62.60%. The small peptides of hydrolysis product were mainly distributed near 613 Da molecular weight composed by 6 amino acids.(3) Through physiological analysis experiment, the Spirulina peptides obtained from laboratory was found antioxidative activity. The ultrafiltrate with molecular weight less than 3 KDa has the strongest DPPH radical scavenging rate, when the concentration of ultrafiltrate was 100 mg/m L, the DPPH radical scavenging rate was 92.25%. Then, the ultrafiltrate were purified sequentially by gel filtration and RP-HPLC, the sequence of the peptide with the highest antioxidative activity was identified to be Pro-Asn-Asn(343.15 Da) using RP-HPLC-ESI-MS. Last, the peptide exhibited good free radical scavenging activity was similar with that of reduced glutathione(GSH). When the concentration was 100 μg/m L, the DPPH radical scavenging rate of the peptide was 81.44% and the GSH was 82.63%.