Study On Preparation, Separation And Bioactivity Of Corn Oligopeptides

As the second largest total corn production country in the world, the main byproduct in corn starch produce by wet-milling process——corn gluten meal(CGM, containing 67%-71% protein), has not been fully used. A large amount of CGM was used to producing feed. This situation has caused a huge waste of vegetable protein resource. In recent years, a lot of research in producing corn oligopeptide, as one kind of ways for effective use of CGM, were carried out. But, there were few reports about amino acid sequence analysis of corn bioactive oligopeptides. In order to provide theoretical reference for the research on structure-activity relationship and new product development, the preparation, separation and antialcoholism activity, hypoglycemic activity of two kinds of bioactive corn oligopeptide, as well as their amino acid sequence analysis of the main composition has been studied in this paper.Using CGM as material, two kinds of bioactive corn oligopeptide was obtained through enzyme hydrolysis by Alcalase. The technology parameters were optimized by single factor test and orthogonal experiment, using degree of hydrolysis and biological activity in vitro(ADH activation rate and alpha glycosidase enzyme inhibition rate) for comprehensive evaluation. The results showed that the optimum condition of preparing COPX were as follows: p H=9.0, temperature=60°C, [E]/[S]=2%, ratio of material and water=1:25, enzymolysis time=3h, the degree of hydrolysis was 22.79%, the ratio of ADH activation can reach 37.54%. The optimum condition of preparing COPJ were as follows: p H=9.5, temperature=60°C, [E]/[S]=1.5%, ratio of material and water=1:15, enzymolysis time=4h, the degree of hydrolysis was 28.58%, the ratio of alpha glycosidase enzyme inhibition can reach 12.37%.Hydrolytic liquid were decolorized with activated carbon powder as decolorising agent. The technology parameters were optimized by single factor test and orthogonal experiment, using decolourization ratio and biological activity in vitro(ADH activation rate and alpha glycosidase enzyme inhibition rate) for comprehensive evaluation. The results showed that the optimum decoloring condition of COPX were as follows: p H=4.0, temperature=40°C, adding amount of activated carbon powder=3%, decoloring time=60min, decolourization ratio was 56.43%, the ratio of ADH activation can reach 34.95%. The results showed that the optimum decoloring condition of COPJ were as follows: p H=5.0, temperature=50°C, adding amount of activated carbon powder=4%, decoloring time=150min, decolourization ratio was 95.44%, the ratio of alpha glycosidase enzyme inhibition can reach 13.74%.Through composition analysis, COPX was found its highly antialcoholism activity may be because the high content of Ala, Leu in COPX. The high amounts of Leu, Ile, Gly, which were considered playing important role to regulate blood sugar, may mainly effect the hypoglycemic activity of COPJ.Through animal experiment in vivo, highly antialcoholism activity of COPX was further confirmed. And, the scavenging rate of blood alcohol concentration was found positively correlated with the dose of COPX.COPX and COPJ was separated with gel filtration chromatography(GFC), and two fractions with highly bioactivity in vitro were obtained: COPX-III、COPJ-II. Then, the two fractions were further separated with RP-HPLC, and another two fractions with highly biological activity in vitro were obtained: COPX-III-17, COPJ-II-13. Finally, UPLC-Q-TOF-MS was used for the separation and purification of COPX-III-17 and COPJ-II-13. The amino acid sequence of the main composition of COPX-III-17 and COPJ-II-13 were: P-Y-L-P-L-L-P-S and A-E-P-N-L-S-G-D-A-P.