玉米蛋白粉是玉米湿法生产淀粉的副产物,含蛋白质质量分数62%~71%。玉米蛋白粉疏水性强的特点限制了其在食品行业的应用。但是,玉米蛋白具有特殊的氨基酸组成,且在其多肽链中存在促酒精代谢、抗氧化等功能区,这为其功能性的表现提供了...玉米蛋白粉是玉米湿法生产淀粉的副产物,含蛋白质质量分数62%~71%。玉米蛋白粉疏水性强的特点限制了其在食品行业的应用。但是,玉米蛋白具有特殊的氨基酸组成,且在其多肽链中存在促酒精代谢、抗氧化等功能区,这为其功能性的表现提供了良好的原料优势。利用碱性蛋白酶（Alcalase）和复合蛋白酶（Protamex）对高底物质量浓度（10 g/100 m L）玉米蛋白进行水解,研究水解条件对蛋白水解物的乙醇脱氢酶（ADH）激活率、·OH清除活性和蛋白回收率的影响。结果表明Alcalase水解玉米蛋白的适宜条件为酶解温度65℃,p H 8.0,加酶量2.5%,时间2h,该条件下蛋白水解物的ADH激活率为18.62%,·OH清除率为82.9%,蛋白回收率为25.08%;Protamex水解玉米蛋白的适宜条件为酶解温度55℃,p H 7.0,加酶量2.5%,时间2 h,该条件下玉米蛋白水解物的ADH激活率为9.67%,·OH清除率为82.0%,蛋白回收率为17.63%。Alcalase和Protamex顺序协同水解（酶底比为1.5%＋1.5%）所得玉米蛋白水解物的ADH激活率达到19.71%,·OH的清除率达到76.7%,蛋白回收率为52.63%。优化条件下蛋白水解物多肽分子量主要分布在955.0~546.8 Da之间。展开更多
Hybrid antioxidants cinnamoyldopamine（2a）, p-coumaroyldopamine（2b）, caffeoyldopamine（2c）, feruloyldopamine（2d） and sinapoyldopamine（2e） were synthesized by conjugation of dopamine（DA） and hydroxycinnamic a...Hybrid antioxidants cinnamoyldopamine（2a）, p-coumaroyldopamine（2b）, caffeoyldopamine（2c）, feruloyldopamine（2d） and sinapoyldopamine（2e） were synthesized by conjugation of dopamine（DA） and hydroxycinnamic acids（HCAs）. The stabilities were studied in buffers at p H 1.3, p H 5.0, and p H 7.4 including the human plasma. All the compounds were found highly stable at acidic p H, but underwent hydrolysis at neutral p H. Furthermore, the hydrolysis proceeded much faster in plasma in the following order as indicated by half-life values（t1/2）, 2c（1.21 h）〈2e（1.52 h）〈2d（1.85 h）〈2b（3.38 h）〈2a（3.88 h）, correlating with the number of electron-donating groups. It has been proven by UV spectrum that 2c, 2d, and 2e displayed red shift of more than 50 nm as compared to 2a and 2b, because of the presence of OH and OCH3 groups. In addition, the compounds（2b–e） showed no cytotoxicity on normal HUVEC cells as DA, although 2a displayed a 16% inhibition of proliferation at 40 μM following 48 h incubation. Their free radical-scavenging activities were evaluated using ABTS^＊＋ and superoxide anion assays and the mechanisms were proposed. It was found that they all exhibited higher activities than trolox, a recognized antioxidant. Amazingly, in the case of the hybrids（2a–e）, their activity was higher than that of HCAs while lower or comparable to that of DA, suggesting that there may be a ＂saturation effect＂ with the hybrid molecules in the antioxidant activities.展开更多
文摘玉米蛋白粉是玉米湿法生产淀粉的副产物,含蛋白质质量分数62%~71%。玉米蛋白粉疏水性强的特点限制了其在食品行业的应用。但是,玉米蛋白具有特殊的氨基酸组成,且在其多肽链中存在促酒精代谢、抗氧化等功能区,这为其功能性的表现提供了良好的原料优势。利用碱性蛋白酶（Alcalase）和复合蛋白酶（Protamex）对高底物质量浓度（10 g/100 m L）玉米蛋白进行水解,研究水解条件对蛋白水解物的乙醇脱氢酶（ADH）激活率、·OH清除活性和蛋白回收率的影响。结果表明Alcalase水解玉米蛋白的适宜条件为酶解温度65℃,p H 8.0,加酶量2.5%,时间2h,该条件下蛋白水解物的ADH激活率为18.62%,·OH清除率为82.9%,蛋白回收率为25.08%;Protamex水解玉米蛋白的适宜条件为酶解温度55℃,p H 7.0,加酶量2.5%,时间2 h,该条件下玉米蛋白水解物的ADH激活率为9.67%,·OH清除率为82.0%,蛋白回收率为17.63%。Alcalase和Protamex顺序协同水解（酶底比为1.5%＋1.5%）所得玉米蛋白水解物的ADH激活率达到19.71%,·OH的清除率达到76.7%,蛋白回收率为52.63%。优化条件下蛋白水解物多肽分子量主要分布在955.0~546.8 Da之间。
基金The National Natural Science Foundation of China(Grant No.21302079)the Fundamental Research Funds for the Central Universities(Grant No.lzujbky-2014-151)
文摘Hybrid antioxidants cinnamoyldopamine（2a）, p-coumaroyldopamine（2b）, caffeoyldopamine（2c）, feruloyldopamine（2d） and sinapoyldopamine（2e） were synthesized by conjugation of dopamine（DA） and hydroxycinnamic acids（HCAs）. The stabilities were studied in buffers at p H 1.3, p H 5.0, and p H 7.4 including the human plasma. All the compounds were found highly stable at acidic p H, but underwent hydrolysis at neutral p H. Furthermore, the hydrolysis proceeded much faster in plasma in the following order as indicated by half-life values（t1/2）, 2c（1.21 h）〈2e（1.52 h）〈2d（1.85 h）〈2b（3.38 h）〈2a（3.88 h）, correlating with the number of electron-donating groups. It has been proven by UV spectrum that 2c, 2d, and 2e displayed red shift of more than 50 nm as compared to 2a and 2b, because of the presence of OH and OCH3 groups. In addition, the compounds（2b–e） showed no cytotoxicity on normal HUVEC cells as DA, although 2a displayed a 16% inhibition of proliferation at 40 μM following 48 h incubation. Their free radical-scavenging activities were evaluated using ABTS^＊＋ and superoxide anion assays and the mechanisms were proposed. It was found that they all exhibited higher activities than trolox, a recognized antioxidant. Amazingly, in the case of the hybrids（2a–e）, their activity was higher than that of HCAs while lower or comparable to that of DA, suggesting that there may be a ＂saturation effect＂ with the hybrid molecules in the antioxidant activities.
