Preparation,Purification and Hypoglycemic Activity of Red Bean Peptide
[Objective]The enzymatic hydrolysis process of red bean protein was screened and the hypoglycemic activity and structure-activity relationship of red bean polypeptide were studied.[Method]The crude protein of red bean was extracted by alkali precipitation and acid extraction method,the best protease was selected according to the yield of peptide,degree of hydrolysis,α-glucosidase inhibition,Fe2+chelation rate and DPPH clearance.The red bean polypeptide was obtained by enzymatic hydrolysis,and the alcohol precipitation polysaccharide was desalted and purified by DA201-C macroporous adsorption resin.The molecular weight and amino acid composition of the polypeptide were measured to explore the structure-activity relationship.[Result]After hydrolysis with four proteases(neutral,alkaline,flavor and compound proteases),the peptide yield of alkaline protease was 82.95%,the degree of hydrolysis was 52.67%,and the optimal α-glucosidase inhibition was 72.14%in the experimental concentration range,which was higher than the other three enzymes.The ratio of peptide to sugar,α-glucosidase inhibition rate(73.49%)and α-amylase inhibition rate(31.31%)were the highest after 85%ethyl alcohol precipitation,and the peptide content was as high as 97.61%after purification.The inhibitory effects on α-glucosidase and α-amylase were 52.49%and 14.63%,respectively,measured at 2 mg/mL.The results showed that the polypeptide of red bean still had independent hypoglycemic activity after removing polysaccharide.Red bean polypeptides were mainly small molecules,accounting for 91.40%less than 3 kDa,and 75.28%less than 1 000 Da.The proportion of hydrophobic amino acids after purification was about 37.28%,and the contents of glycine,alanine,proline and glutamic acid were higher.[Conclusion]Alkaline protease is the best protease for the preparation of red bean polypeptide.The purified red bean polypeptide has hypoglycemic activity,which may be related to the high content of 4 hydrophobic amino acids and the small molecular weight.
red bean polypeptideenzymatic hydrolysis of proteinseparation and purificationhypoglycemicstructure-activity relationship
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