【作者】 高丹丹； 马金谱； 郭鹏辉； 马忠仁； 杨具田；

【Author】 Gao Dandan;Ma Jinpu;Guo Penghui;Ma Zhongren;Yang Jutian;College of Life Science and Engineering,Northwest Minzu University;Biomedical Research Center,Northwest Minzu University;

【机构】 西北民族大学生命科学与工程学院； 西北民族大学生物医学研究中心；

【摘要】 牦牛乳是一种珍稀的天然浓缩乳资源,但目前相关功能性产品和生物制品开发较少。本试验以牦牛乳酪蛋白为原材料,采用课题组从腐乳汁中分离筛选出一株高产蛋白酶菌株SK-01（Bacilus cereus.BG3-7）,对其发酵制备抗氧化肽,利用响应面法优化发酵条件,获得最佳的抗氧化肽制备工艺参数。采用超滤、凝胶层析和HPLC分离纯化牦牛乳酪蛋白抗氧化肽,获得其氨基酸序列为TMPLW,分子量为647.32 Da。进一步构建小鼠D-半乳糖氧化损伤模型,分析多肽对氧化损伤小鼠的保护作用。实验结果表明,牦牛乳酪蛋白抗氧化肽能够缓解小鼠脏器指数的升高,可降低小鼠血清中MDA的含量,其中低剂量组小鼠血清中MDA的含量最低,为0.03 nmol/mL;使SOD和CAT的酶活上升,中剂量组的SOD活性最高,为13.29 U/mL,高剂量组的CAT酶活最高,为10.7 U/g;中剂量组的总抗氧化能力为0.28μmol/mL,GSH含量为13.34μg/mL;同时在mRNA水平上均可使SOD₁、Catalase和GSH₁的表达量上升,高剂量组SOD₁的相对表达量最高（1.47）;Catalase和GSH1的相对表达量正常组均最高,分别为0.98和1.06,说明牦牛乳酪蛋白抗氧化肽能够对机体的氧化损伤起到保护作用。更多还原

【Abstract】 Yak milk is considered a natural concentrated dairy product,but the related functional products and biological products are less developed at present.In this paper,a high-yield protease strain(Bacillus cereus.BG3-7) was isolated from rotten milk and used to prepare antioxidant peptides through fermentation yak casein.Response surface methodology was used to optimize fermentation conditions to improve the activity of antioxidant peptide in casein fermentation broth.Then,ultrafiltration,gel chromatography and high performance liquid chromatography were used to isolate and purify the antioxidant peptides in the fermentation broth,and an antioxidant peptide(TMPLW,647.32 Da) was isolated and purified from yak casein fermentation liquid.Finally,a mouse model of D-galactose oxidative injury was established,and the protective effect of yak cheese protein antioxidant peptide on oxidative injury in mice was analyzed.The results showed that the yak casein antioxidant peptide could increase the visceral index of the mice.Compared with the model group,each experimental group could reduce the content of MDA in the serum of mice to varying degrees.Among them,the content of MDA in the low-dose group mouse serum was the lowest(0.03 nmol/mL).Each experimental group could increase the enzyme activity of SOD and CAT,among which,the SOD activity of the middle-dose group was the highest(13.29 U/mL),and the high-dose group exhibited the highest CAT activity(10.7 U/g).The total antioxidant capacity and GSH content of the middle-dose group were0.28 μmol/mL and 13.34 μg/mL,respectively.In addition,it was found that the yak casein antioxidant peptides enhanced the mRNA expression levels of antioxidant-related genes SOD1,Catalase and GSH1.The mRNA expression level of SOD was the highest in high-dose group(1.47) and mRNA expression levels of Catalase and GSH1 were the highest in the normal group,they were 0.98 and 1.06,respectively.The result indicated that yak milk casein antioxidant peptides could protect the body from oxidative damage.更多还原