Milk samples were collected from 10 cows, in the colostrum (3–4 days) and mature (90 days) lactation stage, to assess the differential expression of all whey proteins and N-glycoproteins. In total, 240 whey proteins and 315 N-glycosylation sites on 214 glycoproteins were quantified. GO annotations, KEGG pathway analysis, and protein classification were performed to understand the similarities and differences of the biological functions of whey proteins and N-glycoproteins among different lactation stages in bovine milk. Furthermore, differential expression of whey proteins and whey N-glycosylated proteins was found between different lactation stages. The related changes of biological functions in differentially expressed proteins were discussed. For example, the increased frequency of glycosylation on lactoferrin and folate receptor alpha occurring in bovine colostrum may provide protection and stimulate development of the newborn calf. Our study thereby improves understanding of variations of glycosylation sites on milk glycoproteins among lactation stages.
The development of food-derived Xanthine Oxidase (XO) inhibitors is critical to the treatment of hyperuricemia and oxidative stress-related disease. Few studies report on milk protein hydrolysates’ XO inhibitory activity, with the mechanism of their interaction remaining elusive. Here, different commercial enzymes were used to hydrolyze α-lactalbumin and bovine colostrum casein. The two proteins hydrolyzed by alkaline protease exhibited the most potent XO inhibitory activity (bovine casein: IC 50 = 0.13 mg mL −1 ; α-lactalbumin: IC 50 = 0.28 mg mL −1 ). Eight potential XO inhibitory peptides including VYPFPGPI, GPVRGPFPIIV, VYPFPGPIPN, VYPFPGPIHN, QLKRFSFRSFIWR, LVYPFPGPIHN, AVFPSIVGR, and GFININSLR (IC 50 of 4.67–8.02 mM) were purified and identified from alkaline protease hydrolysates by using gel filtration, LC-MS/MS and PeptideRanker. The most important role of inhibiting activity of peptides is linked to hydrophobic interactions and hydrogen bonding based on the results of molecular docking and molecular dynamics simulation. The enzymatic hydrolysate of α-lactalbumin and bovine colostrum casein could be a competitive candidates for hyperuricemia-resisting functional food.
危险品化学品经营许可证（带存储）