【作者】 朱艳华；

【导师】 谭军；

【作者基本信息】 华中农业大学 ， 农产品加工及贮藏工程， 2007， 硕士

【摘要】 玉米是世界三大粮食作物之一，又是重要的饲料，由于其单产高，增产潜力大，在农业生产中占有重要的地位。玉米中大部分是淀粉，约占64％～78％，其次是蛋白质，约占8％～14％，还有含量很少的水分、灰分、脂肪、纤维素等。玉米蛋白粉（CGM，俗称玉米渣），是玉米淀粉生产中提取淀粉后主要副产物，大约含有60％的蛋白质，由于口感粗糙，水溶性差，而且从营养学的角度考虑，不是人类理想的蛋白质资源，在食品工业中应用很少，造成环境污染。我国对玉米蛋白粉利用还只是初级阶段。本研究结合我国的具体情况，以玉米蛋白粉为原料制备抗氧化多肽，采用柱层析方法玉米多肽进行纯化，并对其理化性质、抗氧化、抗肿瘤活性进行研究，目的是提高这类原料的附加值，改善其蛋白质的功能特性，减少环境污染，为开创良好的经济与社会效益服务。主要结果如下：1玉米抗氧化肽的制备研究了底物浓度、pH值、加酶量、时间、温度等因素对抗氧化活性的影响，然后在单因素的基础上，进行正交试验进行优化，确定最佳酶解工艺条件为：底物浓度4％、pH值9.5、加酶量1000u／g玉米蛋白粉、温度55℃水解4h。玉米多肽粗品得率为56.21％，蛋白含量为52.68％。多肽粗品经大孔树脂脱盐后得率为为43.96％，蛋白含量为82.69％。2玉米多肽理化性质的研究以玉米多肽的冷冻干燥样品为研究对象，分别研究了玉米多肽的溶解性、表观粘度、起泡性及泡沫稳定性、吸油性等理化性质；分子量大小：氨基酸组成。结果表明：酶解过程明显地改善了玉米蛋白的理化性质；样品利用SepadexG-25柱层析进行纯化，同时测定其分子量范围，得到了两种组分CP-1、CP-2，所占的比例别为5.91％、75.12％，主要组分CP-2分子量主要集中在1000D左右；玉米蛋白水解后苏氨酸、蛋氨酸、异亮氨酸、苯丙氨酸等必需氨基酸含量明显提高。3玉米多肽的抗氧化活性研究用K₃[Fe（CN）₆]测定了玉米多肽的还原力；采用脱氧核糖-铁体系、超氧阴离子自由基体系、二苯代苦味肼基自由基（DPPH·）体系对玉米多肽的抗氧化活性进行了研究；用丙二醛（MDA）试剂盒测定大鼠肝匀浆和肝线粒体中MDA含量，分光光度法测定大鼠肝线粒体肿胀度及大鼠红细胞溶血的影响。结果显示：玉米多肽具有明显的抑制·OH、DPPH·和超氧阴离子的作用；在体外，10.00m／mL玉米多肽使自由基诱导的大鼠肝线粒体MDA生成抑制率达39.63％，对肝组织匀浆MDA生成抑制率分别为22.82％（非诱导组）、45.59％(Fe²⁺诱导组)及67.53％（H₂O₂诱导组）；使自由基诱导的大鼠肝线粒体肿胀度低于对照组；玉米多肽对过氧化氢诱导的大鼠红细胞溶血有明显的抑制作用，但对大鼠红细胞自氧化溶血抑制作用不明显，且在高浓度下有促进溶血的现象发生。4玉米多肽抗肿瘤及免疫活性研究分别以生理盐水为对照组、环磷酰胺组为阳性组，低、中、高玉米多肽剂量组设置试验组，测定小鼠体重增长率、瘤重，小鼠的肝脏指数、脾脏指数，小鼠血清中MDA含量、SOD活力、GSH-Px活力，并对各组小鼠的肿瘤切片进行分析。结果表明：环磷酰胺组、玉米多肽各剂量组均表现出不同程度的抗肿瘤效果。与肿瘤对照组相比，环磷酰胺组的小鼠体重指数、免疫器官指数均表现出显著差异，而玉米多肽组差异不显著，推测玉米多肽是通过提高机体免疫力来实现抗肿瘤效果的。更多还原

【Abstract】 Com is not only one of the three most impotant cereals but also an important feedstuff. For high output and large increasing potential, corn plays an important role in angriculture production. Corn is made up of starch, protein, little water, ash, fat and so on. Starch is an important component in corn, while CGM （Corn gluten meal） is the main byproduct after extracting starch from the corn, having about 60% protein. Because of its bad taste, poor water-solubility and nutrition, application of CGM was limited in food industry. Now researches in CGM re-utilizing in our country is on primary phase. Choosed CGM as the material in this experiment, preparation of Corn peptides, purification, physicochemical properties and bioactivities of Corn peptides were studied, in order to enhance its value, improve its physicochemical properties, and reduce environment pollution as well. The main results were shown as follows:1 Preparation of Corn peptidesEffects of the density of substratum, pH, the amount of protease and hydrolysis temperature of inhibition ability of Corn peptides to hydroxyl radicals（·OH） were studied, and the optimum conditions were determined by singal factors and orthogonal experiment, The optimum technology conditions are: the density of substratum 4%, pH 9.5, the amount of protease 1000u/gCGM and hydrolysis temperature at 55℃for 4 hours. The receiving ratio of coarse Corn peptides was 56.21%, which contains 52.68% protein. After desalting with DA201-C macroporous adsorption resin, the receiving ratio of Corn peptides was 43.96%, which contains 82.69% protein.2 Physieoehemieal properties of Corn peptidesDissolvable ability, viscoce property, foaming characteristics and foam stability, oil-adsorbing ability, molecular weight, amin acid composing of freeze drying production of Corn peptides were studied. The physicochemical properties of CGM were improved obviously by enzymic hydrolysis. Corn peptides were separated into two components: CP-1 and CP-2, accounting for about 5.91% and 75.12%, and the molecular weight of Corn peptides was about 1000D. The essential amino acid such as Thr, Met, Ile, Phe increased after enzymolysis.3 Antioxidant activity of Corn peptidesThe K₃[Fe（CN）₆] was used to evaluate corn peptides’ capacity of deoxidizing; using the DNA-Fe system, superoxide radical(O^2-·) system and the DPPH system·, the antioxidation activities of corn peptides were studied; the reagent kits were used to analyse the content of malondialdehyde （MDA） in mice liver homogenate and mice liver mitochondria; using spectrometer to evaluate hemolysis of mice red blood cell and swelling of mice liver mitochondria. The results showed that Corn peptides was a good reducer and had evident inhibiting effects on free radical of·OH, DPPH·, O^2-·; in vitro, the inhibiting rate of 10.00mg/mL Corn peptides on radical-induced MDA formation was 39.63% in mice liver mitochondria, while 22.82%（without incubation）, 45.59%(incubation with Fe²⁺) and 67.53%（incubation with H₂O₂） in mice liver homogenate; Corn peptides made the radical-induced swelling of mice liver mitochondria much lower than that of mice liver mitochondria without inducement; Corn peptides could inhibit hemolysis induced by H₂O₂ of rat red blood cell, which showed protection activity against oxidation damage of rat red blood cell, but not obviously without incubation.4 Antitumor effects of corn peptides in vivoTake physiological salt as normal control group, the Cy, the lower dose of Corn peptides, the medium dose of Corn peptides, the higher dose of Corn peptides as the test teams, the index of body weigh, lumor weigh, thymus weigh, spleen weigh, the MDA content, the power of GSH-PX and SOD were studied, and then the tumor cells configuration were analyzed. The results showed that the different amount of Corn peptides teams exhibited different tumor-inhibiting effects. The body weigh, the immunity apparatus weigh of Cy team were obviously different from those of normal control group, while those of Corn peptides teams were slightly different. It was infered that Corn peptides could inhibit the tumor through improving the mice immunity.更多还原