大豆低聚肽降胆固醇作用研究

目的:研究大豆低聚肽在降胆固醇方面的作用。方法:取5周龄SD雄性大鼠90只,随机分为6组(每组15只),即Ⅰ(对照组)、Ⅱ(蛋白组)、Ⅲ(多肽组)、Ⅳ(低聚肽组1)、Ⅴ(低聚肽组2)、Ⅵ(低聚肽组3),在实验环境下,构建高胆固醇模型,在对各组继续饲喂高胆固醇饲料的同时,对第Ⅱ组口腔灌喂大豆蛋白,对第Ⅲ组口腔灌喂大豆多肽,对第Ⅳ、Ⅴ、Ⅵ组分别灌喂不同剂量的大豆低聚肽,第Ⅰ组口腔灌喂同体积的饮用水。饲喂6周,分别收集粪便、血清和肝脏,测定血清和肝脏中的胆固醇和甘油三酯含量、粪便重量及其中的类固醇含量。结果:第Ⅱ、Ⅲ、Ⅳ、Ⅴ、Ⅵ组血清和肝脏中的胆固醇和甘油三酯含量均有不同程度的降低,大鼠粪便的排泄量及粪便中类固醇的含量增加。大豆低聚肽组有剂量依赖性,高剂量大豆低聚肽组效果极显著。结论:大豆低聚肽具有比大豆蛋白和大豆多肽更强的降低胆固醇的作用,且这种作用具有剂量依赖性。      

Achyranthes bidentata Polypeptides Reduces Oxidative Stress and Exerts Protective Effects against Myocardial Ischemic/Reperfusion Injury in Rats

Achyranthes bidentata, a Chinese medicinal herb, is reported to be neuroprotective. However, its role in cardioprotection remains largely unknown. Our present study aimed to investigate the effects of Achyranthes bidentata polypeptides (ABPP) preconditioning on myocardial ischemia/reperfusion (MI/R) injury and to test the possible mechanisms. Rats were treated with ABPP (10 mg/kg/d, i.p.) or saline once daily for one week. Afterward, all the animals were subjected to 30 min of myocardial ischemia followed by 4 h of reperfusion. ABPP preconditioning for one week significantly improved cardiac function following MI/R. Meanwhile, ABPP reduced infarct size, plasma creatine kinase (CK)/lactate dehydrogenase (LDH) activities and myocardial apoptosis at the end of reperfusion in rat hearts. Moreover, ABPP preconditioning significantly inhibited superoxide generation, gp91^phox expression, malonaldialdehyde formation and enhanced superoxide dismutase activity in I/R hearts. Furthermore, ABPP treatment inhibited PTEN expression and increased Akt phosphorylation in I/R rat heart. PI3K inhibitor wortmannin blocked Akt activation, and abolished ABPP-stimulated anti-oxidant effect and cardioprotection. Our study demonstrated for the first time that ABPP reduces oxidative stress and exerts cardioprotection against MI/R injury in rats. Inhibition of PTEN and activation of Akt may contribute to the anti-oxidant capacity and cardioprotection of ABPP.     

Synthesis of novel zwitterionic polymers and their properties as filtrate reducer for water-based drilling fluid

The development of high-temperature and salt-resistant filtrate reducer is of great significance to the exploitation of deep and ultra-deep wells. In this study, Zwitterionic copolymer PANDS was synthesized by free radical polymerization using acrylamide (AM), N-vinylpyrrolidone (NVP), methacryloxyethyl trimethyl ammonium chloride (DMC) and sodium p-styrene sulfonate (SSS) as monomers. Through orthogonal test, the optimum synthesis conditions were determined as follows: n (AM): n (NVP): n (SSS): n (DMC) = 3.5:2:0.5:0.5, the reaction temperature is 50°C, the initiator concentration is 0.4 wt%. The structure and thermal stability of the copolymers were analyzed by Fourier transform infrared spectroscopy (FT-IR), nuclear magnetic resonance spectroscopy (¹H-NMR) and thermogravimetry (TG). In addition, the filtration reduction performance of PANDS was evaluated according to the American Petroleum Institute (API) standard. The mechanism of reducing filtration loss was studied by laser particle size analysis, Zeta potential and scanning electron microscope analysis of mud cake. The results show that PANDS has good temperature resistance and good filtrate loss reduction. With the addition of 1.5%PANDS, the filtrate loss of drilling fluid is 8.7 mL after aging at 160°C for 16 h, and can resist 6 wt% NaCl and 1 wt% CaCl₂.     

Beer Polypeptides and Silica Gel Part II. Polypeptides Involved in Foam Formation

Beer contains approximately 500 mg/L protein depending on the brewing procedures employed. This protein is in the form of polypeptides, the majority of which lie within the 10–40 kD size range. Some of these polypeptides are responsible for causing colloidal haze, some enhance foam stability and the remainder appear to have no function in beer except to contribute to mouth‐feel. Those polypeptides involved in haze formation were described in a previous paper. To continue these studies, data is presented to show that foam polypeptides are highly glycosylated and that purified foam glycoprotein contains low levels of the amino acid proline. As silica preferentially adsorbs polypeptides rich in proline, it is unlikely to adsorb this material and damage foam stability. The molecular sizes and composition of glycoproteins recovered from untreated beer, purified foam and beer from which the foam component has been removed are presented. These fractions include the polypeptides responsible for foam stability and those that appear to have no role in physical stability.     

鮰鱼皮明胶ACE抑制肽降血压活性的研究

鮰鱼皮为斑点叉尾鮰鱼片加工的主要副产物,利用鮰鱼皮明胶制备降血压肽(ACE抑制肽)可为鮰鱼皮的高值化利用提供参考。本文通过对原发性高血压大鼠(SHR)进行一次性及长期给药(28 d)实验,研究鮰鱼皮明胶ACE抑制肽(Mr3000 Da)的降血压作用,并测定大鼠血清和肺组织中的ACE活性和Ang II含量。实验结果表明:一次性给药和长期灌胃给药鮰鱼皮明胶ACE抑制肽均对SHR大鼠有显著降血压作用,降血压效果呈剂量依赖性;高剂量组SHR大鼠灌胃给药2 h后,其收缩压由206 mmHg降至159 mmHg;高剂量组SHR大鼠经长期灌胃给药10 d后,血压一直保持在155 mmHg左右;同时,鮰鱼皮明胶ACE抑制肽对正常血压大鼠的降血压作用不显著。鮰鱼皮明胶ACE抑制肽对SHR大鼠血清和肺组织中的ACE活性有显著的抑制作用,从而使大鼠血清和肺组织中Ang II含量显著降低,而对正常血压的SD大鼠的血清和肺组织中ACE活性和Ang II含量影响不显著。     

乌贼墨多肽诱导人前列腺癌DU-145细胞凋亡的机制研究

本文探讨了乌贼墨多肽(SHP)诱导DU-145细胞凋亡机制。采用CCK-8法检测SHP对DU-145细胞增殖的影响;采用HE染色和AO/EB荧光染色观察DU-145细胞的形态学的变化;采用流式细胞术检测细胞早期凋亡率;并通过Western Blotting检测细胞中p53、Bcl-2、Bax、Caspase-3、VEGF的蛋白表达变化。结果表明,SHP对DU-145细胞的增殖具有明显的抑制作用且呈现剂量和时间依赖性;SHP作用后的DU-145细胞出现凋亡的形态学特征;流式细胞术结果显示,随着SHP浓度和作用时间的增加,DU-145细胞的早期凋亡率从12.25%增加到34.20%;Western Blotting结果显示,当SHP作用24 h后,VEGF、Bcl-2蛋白表达量降低,p53、Bax、Caspase-3蛋白表达量增加。综上可知,SHP能够诱导DU-145细胞凋亡,其机制有可能是通过激活抑癌基因p53,下调Bcl-2/Bax比例;下调VEGF,激活凋亡蛋白酶Caspase-3,诱发凋亡级联反应来实现的。     

EFFECTIVENESS OF THE ELECTROENDOSMOTIC PREPARATIVE ELECTROPHORESIS FOR THE PURIFICATION OF ALL PROTEINS AND POLYPEPTIDES FROM BEER

Ammonium sulphate precipitated beer proteins and polypeptides were fractionated by electroendosmotic preparative electrophoresis in the presence of sodium dodecyl sulphate. This one-step procedure allowed the contemporary purification of all beer proteins and polypeptides with molecular masses ranging from 6 up to 45 kDa. The obtained resolution was higher than that of any other technique, including analytical electrophoresis, since protein bands with minimal differences in molecular mass were collected pure in separated fractions. This procedure allows the recovery of purified beer components with minimal work, accordingly it can be considered a very useful tool for the preparation of fractions to be characterized and/or used for antibodies production.     

金属酚醛/两性离子聚合物涂层聚丙烯补片的制备及其抗蛋白吸附性能

为将亲水两性离子材料与惰性聚丙烯(PP)补片有效结合,降低蛋白质在补片表面的吸附,利用三价铁离子和单宁酸(TA)层层自组装的金属酚醛网络(MPN),介导聚羧酸甜菜碱甲基丙烯酸酯(PCBMA)固定在PP补片上,对该改性涂层补片的微观形貌、表面成分、接触角、表面电位、力学性能、抗蛋白吸附性能和细胞毒性进行表征与分析。结果表明:MPN可将PCBMA均匀固定在单丝表面,改变补片的表面化学组成;PCBMA-Fe/TA涂层将PP表面的水接触角降低至37°,表面电位由-55.7 mV提高到-5.14 mV;涂层不影响PP补片的力学性能,并为补片带来了显著的抗蛋白吸附效果;改性补片的相对细胞活力达到89%,表现出良好的生物相容性。研究结果有望为惰性医疗器械的抗污改性提供参考。     

南极磷虾肽制备工艺优化及抗氧化测定

目的:优化南极磷虾肽的提取工艺。方法:选取料液比、加酶量、温度、pH以及时间5因素,在单因素实验的基础上采用L9(34)正交实验,计算各组酶解液的水解度。结果:正交分析软件得到木瓜蛋白酶对磷虾最佳的酶解条件为:料液比1:2,加酶量3000U/g,酶解温度55℃,酶解pH7.0,酶解时间3h,验证实验测得最优条件下水解度达24.73%。结论:酶解液经浓缩、喷雾干燥后,得到淡黄色具虾香味的粉末,得率6.48%,多肽含量达87.32%,通过与维生素E的比较,表明其在抗氧化方面具有良好的清除自由基的能力,说明该方法制备得到的南极磷虾肽在实际生产中有较为广阔的应用前景。