玉米醇溶蛋白肽的超滤膜分级及产物的体外生物活性

为探究分子质量对玉米醇溶蛋白肽体外生物活性的影响，以玉米醇溶蛋白为原料，采用碱性蛋白酶Alcalase酶解制备玉米醇溶蛋白肽，采用截留分子质量为5、3 ku和1 ku的超滤膜对玉米醇溶蛋白肽进行顺次分级分离，获得分子质量大于5 ku、3~5 ku、1~3 ku和小于1 ku 4个组分，通过测定各组分的抗氧化活性和乙醇脱氢酶激活活性，表征超滤膜分级对玉米醇溶蛋白肽体外生物活性的影响。结果表明：用碱性蛋白酶Alcalase酶解玉米醇溶蛋白2 h时，清除DPPH自由基的玉米醇溶蛋白肽组分分子质量分布在1~5 ku范围内；螯合亚铁离子、清除羟自由基和激活乙醇脱氢酶的玉米醇溶蛋白肽组分的分子质量集中在小于1 ku；而玉米醇溶蛋白肽的超氧阴离子自由基清除活性和还原力受其分子质量大小影响较小。综上，分子质量对玉米醇溶蛋白肽的生物活性影响较大，可以选用超滤膜对玉米醇溶蛋白肽活性组分进行分级和富集。

Ultrafiltration membrane classification of zein peptide and the in vitro biological activities of the product

In order to study the effect of molecular weight on the in vitro biological activities of zein peptide, zein was hydrolyzed by alkaline protease Alcalase to prepare zein peptide, and then the zein peptide was fractionated sequentially using ultrafiltration membranes with molecular weight cut-off 5,3 ku and 1 ku, and four components with molecular weight more than 5 ku, 3-5 ku, 1-3 ku and less than 1 ku were obtained. The effect of molecular weight on the biological activities of zein peptide was characterized by measuring the antioxidant and alcohol dehydrogenase activation activities of each molecular weight component. The results showed that when zein was hydrolyzed with alkaline protease Alcalase for 2 h, the molecular weight of the zein peptide that had the ability to scavenge DPPH free radicals was in the range of 1-5 ku. The molecular weight of the zein peptide with the ability to chelate ferrous ions, scavenge hydroxyl free radicals and activate alcohol dehydrogenase was concentrated less than 1 ku. However, the superoxide anion radical scavenging activity and reducing power of zein peptide were less affected by the molecular weight. In conclusion, the biological activities of zein peptide were greatly affected by the molecular weight, and ultrafiltration membranes could be used to fractionate and concentrate the active components of zein peptide.