甲基对硫磷压电免疫传感技术的初步探讨

分别利用蛋白A法和巯基自组装膜法将抗体固定在压电石英晶体金电极上,结果表明巯基自组装膜法效果更好。在利用巯基自组装膜法固定甲基对硫磷抗体的基础上,初步建立了基于直接法和竞争法的甲基对硫磷压电免疫传感技术并对两种技术作了比较,结果表明,基于竞争法的压电免疫传感技术对对硫磷抗原抗体反应的响应频移值较大,可提高检测灵敏度,降低检测限。     

Oxidative stress in the erythrocytes of cattle intoxicated with Senecio sp

BACKGROUND: Intoxication caused by Senecio sp is characterized by irreversible damage to liver cells and may be associated with oxidative stress. OBJECTIVES: The aim of this study was to evaluate the effects of intoxication by Senecio sp on lipoperoxidation, antioxidant defenses, and the osmotic resistance of erythrocytes in cattle. METHODS: Blood samples from 30 intoxicated animals (group 1) and 30 healthy animals (group 2) were analyzed. The diagnosis of poisoning by Senecio sp was based on histopathologic lesions verified through hepatic biopsy. The following biochemical parameters of oxidative stress in the erythrocytes were determined: thiobarbituric acid-reactive substances (TBARS), copper-zinc superoxide dismutase (CuZnSOD) activity, and nonprotein sulfhydryl (NPSH) groups. Erythrocyte osmotic fragility also was evaluated. RESULTS: TBARS concentration and CuZnSOD activity were significantly (P <.001) higher in group 1 when compared with group 2. The concentration of erythrocyte NPSH groups was significantly (P <.03) lower in group 1 when compared with group 2. Osmotic fragility was more pronounced in the erythrocytes of group 1 when compared with group 2 (P < .001). CONCLUSIONS: The results of this study indicate that poisoning by Senecio sp causes an increase in lipoperoxidation, oxidation of NPSH groups, and consequently, oxidative stress in bovine erythrocytes that may contribute to hemolysis. These findings may contribute to a better understanding of the mechanisms involved in cell damage in animals intoxicated by Senecio sp.     

小麦面粉蛋白质量评价模型构建及蛋白质量再评价

小麦面粉蛋白的含量和类型决定着小麦面粉的加工品质。为量化比较小麦面粉蛋白对品质影响的差异,以11个不同品质类型的品种为材料,分析了面粉蛋白巯基集团与面粉质量的相关性,发现自由巯基含量与面团稳定时间有极显著正相关性,与面筋指数有显著正相关性;基于面粉蛋白的自由巯基和分子内二硫键含量差异,建立了一个简单的品质贡献量化评价模型;依托蛋白质巯基预测结果,对90个不同类型的面粉蛋白的品质贡献进行了量化比较。结果表明,高分子量麦谷蛋白亚基中得分较高的是1Dy10、DX5和1Dy3;低分子量麦谷蛋白亚基中,位于 Glu-B3、 Glu-D3位点的蛋白得分达到7.2分,高于高分子量麦谷蛋白最高分的1Dy10(6.3分)。因为低分子量麦谷蛋白在面粉中的含量远超高分子量麦谷蛋白,推测面团强度的主要决定因素是低分子量麦谷蛋白,而不是传统观点认为的高分子量麦谷蛋白亚基。另外,一些燕麦类似蛋白和部分醇溶蛋白也对面团强度有一定贡献。     

真空和面对面条面团谷蛋白大聚合体含量及粒度分布的影响

明确真空和面对低水分面条面团中谷蛋白大聚合体(glutenin macropolymer,GMP)特性的影响,有助于探讨真空和面改善面条质地的化学结构基础,该研究以3个小麦品种(郑麦366、宁春4号、济麦22)磨制的面粉为材料,在不同真空度(0、0.06、0.08 MPa)下和面,和面时间为8 min,测定面团中GMP含量及粒度分布,并采用Ellman试剂比色法分析蛋白质和GMP中游离巯基含量的变化。结果表明,与非真空和面相比,0.06 MPa制作的面团中GMP含量较高,而过高的真空度(0.08 MPa)会导致GMP含量降低。真空和面对面团中GMP粒度分布有显著影响,济麦22和宁春4号面团在0.06 MPa时大粒径GMP所占体积、表面积和数目百分比显著高于0和0.08 MPa(P0.05),而郑麦366在0.08 MPa时大粒径GMP所占体积百分比显著较高。真空度为0.06 MPa时,济麦22和宁春4号面团中的游离巯基含量显著低于0和0.08 MPa(P0.05);而对于郑麦366,0.08 MPa制作的面团中游离巯基含量显著低于非真空和面。对于2种中筋小麦粉(济麦22和宁春4号),适宜真空度和面会使GMP中更多的游离巯基参与二硫键交联。结论认为,适宜真空度和面可以提高面团中蛋白质聚合度;与蛋白质和湿面筋含量高、面团强度大的郑麦366相比,2种中筋小麦粉面团中GMP特性受真空度变化的影响更明显。研究结果为揭示真空和面的作用机制、深入认识面筋蛋白在面条加工中的作用提供参考。     

The impact of redox agents on further dough development,relaxation and elastic recoil during lamination and fermentation of multi-layered pastry dough

The role of gluten proteins during lamination and fermentation of multi-layered wheat flour pastry dough was examined by including oxidizing or reducing agents in the recipe to respectively strengthen or weaken the gluten protein network. Pastry burst rig textural measurements showed that dough strength increases during lamination up to 16 fat layers. However, further lamination up to 64 and 128 fat layers decreases the dough strength, most likely due to destruction of layer integrity. Redox agents strongly affect dough strength. Furthermore, fermentation and spread tests showed that they strongly influence elastic recoil immediately after lamination and during relaxation. Moreover, elastic recoil consistently occurs to a greater extent in the final direction of sheeting. None of the observed changes in dough strength and relaxation behaviour could be linked to changes in the levels of protein extractable in sodium dodecyl sulfate containing medium (SDS-EP). This suggests that changes occur preferentially either within the SDS-extractable or within the non-SDS-EP fraction and that they do not render non-extractable protein fractions extractable or vice versa. Furthermore, elastic recoil is most likely caused by reformation of inter- and intramolecular hydrogen bonds and hydrophobic interactions.     

Localization of Zn-binding protein in the digestive tract tissue of common carp

ABSTRACT: The concentrations of Zn and sulfhydryl (SH) groups in the digestive tract tissue of common carp and some aquatic animals were studied. It was found that Zn and bound SH groups could be used as indicators for detecting the Zn-binding protein in the digestive tract tissue of common carp. The digestive tract tissue of the fish underwent subcellular fractionation, and it was found that the nuclei/cell debris fraction contained most of the DNA (85%), Na⁺/K⁺-ATPase (82%), organic phosphate (90%) and the Zn-binding protein (79%), but only part of the 5'-nucletidase and alkaline phosphatase (<23%). The nuclei/cell debris fraction of the digestive tract tissue of common carp was treated with either collagenase type I or type IV, and subfractionated by sucrose density centrifugation. It was found that treatment with collagenase type IV could release more than 50% of the Zn-binding protein, Na⁺/K⁺-ATPase and organic phosphate from collagen. Sections of digestive tract tissue of common carp were stained for Zn. It was observed that Zn can be found mainly on the edge of the epithelial layer, and everywhere in the 'membrane-like' portion of the submucosal and muscular layers. It is proposed that most of the Zn-binding protein in the digestive tract tissue of common carp is located on the basolateral plasma membranes of the epithelial cells and on the surrounding muscle cells that are attached to the collagen type IV of basal laminae.     

巯基改性生物炭对水中甲基汞的吸附

为探讨巯基改性生物炭对甲基汞的吸附特征及机理,以牛粪、污泥、竹屑为原料制备热解生物炭,并利用3-巯丙基三甲氧基硅烷分别对其改性,采用元素分析、电镜扫描和傅里叶变换红外光谱仪对改性前后的生物炭进行表征,结合等温吸附实验和吸附动力学实验,对比研究不同原料改性生物炭对甲基汞的吸附性能并探讨其吸附机理。结果表明:通过O—Si基团的成功引入证明巯基改性成功,巯基改性后的生物炭对甲基汞的吸附能力增强,主要归因于含硫基团(—SH、C—S)与甲基汞离子有较强的络合能力。改性后,3种生物炭对甲基汞的吸附符合准二级吸附动力学和Langmuir等温吸附方程。巯基改性生物炭对甲基汞的最大拟合吸附量达到526~1450ng·g^-1,显著高于未改性生物炭(331~533 ng·g^-1),改性组生物炭的吸附速率常数k₂(1.800~2.640)明显高于未改性组生物炭(0.014~0.156)。研究表明,巯基改性生物炭吸附甲基汞主要是通过其表面引入的—SH和C—S等官能团,与甲基汞形成—SHgCH₃和(CH₃Hg)₂S等络合物,从而有效去除水中甲基汞。