人白细胞介素-2提纯样品中PHA残留量测定

应用SDS梯度聚丙烯酸胶凝胶电泳法、淋巴细胞增殖法和显微血凝法对三批提纯人IL-2样品中的残留PHA作了检测·结果表明我们提纯工艺对去除PHA效果较好，PHA残留浓度低于25μg／ml，PHA总量从提纯前的600mg降为0．75mg以下．去除率达99％以上，另外，我们还对三种检测方法进行了比较，认为显微血凝法是一种简便、特异、灵敏的方法。     

Detection of soybean antigenicity and reduction by twin-screw extrusion

Antiserum toward soybean meal was prepared by feeding a soybean meal diet containing large amounts of antigens to calves. The antiserum was used to develop a sensitive detection method for soybean meal antigens by competitive inhibition enzyme-linked immunosorbent assay. With this method, the effectiveness of twin-screw extrusion cooking in reducing antigenicity in soybean meal was examined. Antigenicity was reduced to 0.1% of the original activity by extrusion cooking with screws containing kneading-disc elements and die-end temperatures exceeding 66°C. Electrophoretic analysis of the cooked meal indicated that the reduction in antigenicity was due to degradation of protein structures, particularly those with molecular weights exceeding 40 kDa.     

Comparison of Electrophoretic Protein Profiles from Sheep and Goat Parotid Saliva

Saliva provides a medium for short-term adaptation to changes in diet composition, namely, the presence of plant secondary metabolites. Salivary proteins have biological functions that have particular influence on oral homeostasis, taste, and digestive function. Some salivary proteins, such as proline-rich proteins, are present in browsers but absent in grazers. Despite the significance of salivary proteins, their expression patterns in many herbivores are unknown. We investigated the sodium dodecyl sulfate-polyacrylamide gel electrophoresis profile of parotid salivary proteins from two domesticated species, one a grazer, the sheep, Ovis aries, and the other a mixed feeder, the goat, Capra hircus, both fed on the same conventional diet. With 12.5% polyacrylamide linear gels, we observed uniform patterns of salivary proteins within the two species. In the goat profile, 21 major bands were observed, and 19 in the sheep profile. Each band was subjected to peptide mass fingerprinting for purposes of identification, allowing for 16 successful protein identifications. Marked differences were observed between the species in the region of 25–35 kDa molecular weights: one band was present in significantly different intensities; three bands were present only in goats; and one band was present only in sheep. This is the first report of a comparison of the protein salivary composition of sheep and goats and suggests that future research should be conducted to reveal a physiological function for salivary proteins related to the differences in feeding behavior of these species.     

Electrophoretic Characterization and Functional Properties of Rice Proteins from Indian Rice Cultivars

Rice protein isolates and extracts of protein fractions were prepared from Indian rice cultivars, namely, Jaya, HKR-120, P-44, Sharbati, Bas-370, and HBC-19. The protein extracts were characterized using SDS-PAGE. The total protein contents of rice cultivars ranged from 5.46 to 7.02 g/100 g sample with albumin and glutelin fractions showing the highest variability among rice cultivars. The electrophoretic patterns of protein fractions exhibited many varietal differences with glutelin fraction revealing the most heterogeneous (10–17 polypeptide units) and prolamin fraction revealing the most homogenous polypeptide composition (3 polypeptide units). The alkali extracted rice endosperm protein isolates showed favorable emulsifying and foaming capacities particularly at an alkaline pH of 11. The total protein content was significantly correlated positive with foaming capacity (r = 0.917, p < 0.01) and negative with oil absorption capacity (r =??0.914, p < 0.05). The total protein content was also correlated significantly positive with cooking time (r = 0.956, p < 0.01) and cooked grain hardness (r = 0.966, p < 0.01).     

Identification of an acidic α-amylase from Alicyclobacillus sp. A4 and assessment of its application in the starch industry

An acidic α-amylase was purified from thermoacidophilic Alicyclobacillus sp. A4 by ion exchange chromatography with 22% recovery, and showed a molecular mass of 64 kDa by SDS-PAGE. Its amino acid sequence was determined by sequencing three internal peptides and the complete genome of strain A4, and shared highest identity (64%) with Alicyclobacillusacidocaldarius α-amylase. Compared with other reported α-amylases, the purified enzyme had some distinct characteristics. The optimal activity was found to occur at 75 °C and pH 4.2, similar to the glucamylase widely used in the starch industry. The enzyme was Ca²⁺ independent, and had strong ability to digest raw starch (96.71%) with commercial glucamylase in one step. These properties of the purified enzyme make up the deficiency of the commercial α-amylases currently used and avoid repeated adjustment of pH and temperature in double-enzymatic sugar-making process. The purified enzyme will be commercially valuable in the starch industry.     

Caffeate derivatives induce apoptosis in COLO 205 human colorectal carcinoma cells through Fas- and mitochondria-mediated pathways

The objective of this study was to investigate the anticancer activity of caffeate derivatives in human cancer cells. Our results demonstrate that caffeate derivatives decreased the population growth of COLO 205, assessed using the MTT assay. However, caffeate derivatives, at the concentrations used in this study (0-250 μM) did not affect the viability of HepG2, Huh7, PLC5, and SK-Hep-1 cells. Flow cytometric analysis of COLO 205 cells exposed to decyl caffeate showed that the number of apoptotic cells increased in a time- and dose-dependent manner. Western blot analysis revealed that decyl caffeate stimulated an increase in protein expression levels of p53, Fas, FasL, AIF, and Apaf-1. Additionally, treatment with decyl caffeate changed the expression levels of Bcl-2 family members and subsequently induced the activation of caspase-12, caspase-9, and caspase-3, which was followed by cleavage of PARP. Our findings highlight the chemopreventive potential of decyl caffeate.     

蛋壳膜中胶原蛋白的提取分离

以废弃的鸡蛋壳为原料,采用酶法对鸡蛋壳膜中的胶原蛋白进行提取,探讨胶原蛋白提取的最佳条件。结果得出,壳膜的最佳分离条件为0.5 mol/L盐酸,pH7.0,温度30℃,固液体积比1∶10,反应时间1 h;胶原蛋白的最佳提取条件为0.5 mol/L醋酸,胃蛋白酶5%(150 U/g),温度40℃,pH2.5,提取体积1∶10,反应时间24 h。     

酒度、总酸、pH值以及饮用温度对干红葡萄酒涩味的影响

利用十二烷基硫酸钠-聚丙烯酰胺凝胶电泳（sodium dodecyl sulphate polyacrylamide gel electrophoresis,SDS-PAGE）分析唾液蛋白与模拟酒反应后蛋白减少比例,并将其表示为涩味强度;同时,以酒度、总酸、pH值以及饮用温度为考察因素,利用二次正交旋转组合设计分析各因子对涩味强度的影响。结果表明：pH值对涩度影响最大,其次是酸度和温度,酒度影响最小;其中pH值和酸度互作效应对涩味的影响显著。     

不同预处理方式对碱法提取米渣蛋白得率的影响

研究不同的预处理方式对碱法提取米渣蛋白得率的影响。结果表明：分别用质量分数0.5%柠檬酸或稀释20倍的醋酸（0.875 mol/L）对米渣在25 ℃处理180 min,再用0.1 mol/L NaOH溶液提取,温度50 ℃,提取时间27 h,则蛋白提取率有较大提高;蛋白质提取率分别为84.60%和80.1%,高于未经过酸处理的米渣蛋白提取率。质量分数为0.5%柠檬酸和稀释20 倍（0.875 mol/L）的醋酸预处理的大米渣蛋白质经十二烷基硫酸钠-聚丙烯酰胺凝胶电泳分析表明,用体积分数18%分离胶有利于蛋白质电泳的分离;蛋白质在提取过程中分解成小的片段,主要集中在9.5 kD和4.1 kD附近,其中4.1 kD蛋白含量较多,且用质量分数0.5%柠檬酸预处理后碱法提取的蛋白质颜色纯白鲜亮,质地细腻润滑。     

蟹类主要过敏原的模拟肠胃液消化及其对过敏原活性的影响

目的:通过模拟肠胃液消化试验,分析锯缘青蟹肌肉中过敏原(原肌球蛋白)的消化特性以及消化对过敏蛋白致敏性的影响.方法:采用美国药典提供的模拟胃、肠液配方,测定青蟹原肌球蛋白和肌原纤维蛋白在体外模拟肠胃环境中的消化稳定性.以十二烷基硫酸钠-聚丙烯酰胺凝胶电泳(SDS-PAGE)和免疫印迹法(Western-blot)进行分析.结果:在模拟胃液反应中,非过敏原蛋白尤其是肌球蛋白重链和肌动蛋白等被胃蛋白酶快速降解,而原肌球蛋白在60 min时仍未被完全分解.在模拟肠液反应中,相对于致敏蛋白,肌球蛋白重链、肌动蛋白等非过敏蛋白在较短的时间内被分解,原肌球蛋白尽管120 min后几乎被完全分解,但会产生一些较稳定的蛋白降解片段.以免疫印迹法检测过敏患者血清,结果分子质量为34 kDa的原肌球蛋白降解产物仍具有过敏原性.结论:蟹类过敏蛋白相对于非过敏蛋白具有较高的消化稳定性,而且其高分子质量降解产物仍可能引起过敏反应.