以3种粳稻和3种籼稻米糠为原料,通过高压均质-酶法制备米糠多肽,对酶解液中的多肽进行分离纯化及结构鉴定,探究其抗氧化机制。以肽含量和还原力为指标,最佳提取工艺为均质压力60 MPa、料液比1∶15 (g∶mL)、酶添加量3 200 U/g、酶解时间2 h、pH 10、温度55 ℃。筛选出抗氧化活性最高的蛋白酶解液进行超滤、葡聚糖凝胶Sephadex G-25分离纯化和LC-MS/MS鉴定后,得到60条具有潜在活性的肽。分子对接结果表明,多肽YGGGY的结合自由能最低,在CD38蛋白(NAD+降解酶)的活性位点通过氢键、范德华力、盐桥等产生相互作用,暗示着其具有潜在抑制NAD+降解酶活性的功能,从而使机体能够保持足够的NAD+含量以应对氧化应激损伤,延缓机体衰老。该研究为分析、解释米糠肽的分子机制提供了科学理论依据,也为全谷物产品的开发提供依据。
Rice bran peptides were extracted by high-pressure homogenization-assisted enzymatic extraction technology from three varieties of indica rice bran and three varieties of japonica rice bran.The peptides in the enzymatic hydrolysate were separated, purified and identified to investigate their anti-aging mechanism.Results showed that the optimal extraction conditions for rice bran peptides based on peptide content and reducing power when the homogenization pressure was 60 MPa, the material-to-liquid ratio was 1∶15 (g∶mL), enzyme dosage was 3 200 U/g, enzymolysis time was 2 h, pH was 10, and enzymolysis temperature was 55 ℃.The protein hydrolysate with the highest antioxidant activity has been identified.Totally sixty peptides with good activity were obtained through ultrafiltration, Sephadex G-25 separation and purification, and LC-MS/MS analysis.The results of molecular docking showed that the peptide YGGGY had the lowest binding free energy, and it interacts with the active site of the CD38 protein (NAD+ degrading enzyme) through hydrogen bonding, van der Waals forces, salt bridges, etc.This suggested that it had the potential function of inhibiting the activity of the NAD+ degrading enzyme so that the organism could provide sufficient NAD+ content against oxidative stress and slow down aging.It provides a scientific basis for analyzing and interpreting the antioxidant mechanism of rice bran peptide and for the development of whole grain products.
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