BSA修饰Fe_3O_4纳米颗粒用于苦瓜提取液中活性成分的筛选

用一步法直接合成了表面氨基化修饰的Fe3O4纳米颗粒(NH2-MION),通过双功能团试剂戊二醛将牛血清白蛋白(BSA)固定在NH2-MION表面,将BSA-MION用于苦瓜提取液中活性成分的筛选,利用气相色谱-质谱联用技术鉴定出了3种与BSA作用较强的活性成分。     

棉酚及其氧化物与牛血清蛋白相互作用的研究

利用紫外-可见吸收光谱和荧光光谱法研究棉酚及其氧化物与牛血清蛋白(bovine serum albumin,BSA)的结合作用。实验结果表明,棉酚及其氧化物与牛血清蛋白相互作用而引起的荧光猝灭机制均属于动态和静态的联合猝灭,BSA发射峰蓝移。通过计算各个结合参数得出:棉酚及其氧化物与BSA的结合常数在105数量级,说明棉酚及其氧化物与BSA有很强的结合,结合位点均为1;热力学参数ΔH0、ΔS0和ΔG0,表明棉酚及其氧化物与BSA结合的主要作用力为疏水作用力和氢键。根据Forster的非辐射能量转移理论,计算供体(BSA)与受体(棉酚及其氧化物)间的结合距离r分别为2.94 nm和3.12 nm,它们都能以能量转移的方式与BSA发生作用。紫外-可见光谱、同步荧光光谱和三维荧光光谱的研究结果表明,棉酚及其氧化物与BSA的结合引起了BSA的构象变化。     

Determination of testosterone esters and nortestosterone esters in animal blood serum by LC-MS/MS

A sensitive and robust confirmatory method for determination of steroid esters in blood serum is essential for reliable monitoring of possible illegal use of steroid hormones as growth promoters in meat production. A previously used sample preparation methodology was improved. The procedure consists of protein precipitation and removal of phospholipids by dispersive SPE Supel? QuE Z-Sep (Sigma-Aldrich) followed by clean-up on alumina column and LC-MS/MS measurement. The modified method has been validated according to Commission Decision 2002/657/EC. Validation parameters for determination of six testosterone esters and five nortestosterone esters in bovine and porcine blood serum are presented in this article. Decision limits for all analytes were observed in the range 10–20 pg mL^?1. The method described is considerably robust for bovine and porcine serum analyses and can be applied both for screening and confirmatory determination in routine residue monitoring.     

Factors affecting in vitro formation of tannin-protein complexes

In interaction of condensed tannins from Desmodium intortum and Lotus pedunculatus and tannic acid (hydrolysable tannin) with salivary mucoproteins (from sheep and goats), plant leaf proteins and bovine serum albumin were evaluated. These studies were carried out over a pH range of 2-0-9-0 and different inorganic ion conditions to simulate conditions in which dietary proteins would interact with tannins in a ruminant digestive tract. Insoluble tannin-protein interactions were found at pH 4–5–5–5 for bovine serum albumin and 3–5–5–5 for plant leaf protein. The present study showed that pH alone was not the sole determinant for tannin-protein complex formation, since tannin-protein complexation was found in the pH range 6-0–6-5 when different inorganic ions were added to the solutions. Insoluble complexes were not formed with salivary proteins, although precipitation by tannic acid was achieved at 5°C. This suggests that tannins may form soluble rather than insoluble complexes with salivary proteins. It was concluded that purified F1 leaf protein (the major protei occurring in leaf tissue) ought to be used as the test protein for evaluating tannin-protein interactions for in vitro assay procedures. Using this method it was calculated that 27–43% and 19–40% of available plant protein may interact with condensed tannins from Desmodium intortum and Lotus pedunculatus, respectively.     

聚丙烯酰胺凝胶电泳研究硫酸铵盐析分离猪血清IgG

通过聚丙烯酰胺凝胶电泳对硫酸铵盐析分离猪血清G型免疫球蛋白进行了研究，结果显示pH值7．4时，猪血清IgG主要沉淀区间为硫酸铵饱和度25-40％，10倍稀释猪血清IgG最佳硫酸铵沉淀参数为：pH值7．4，硫酸铵饱和度37％，此时IgG得率为80．5％，纯度为72．9％。沉淀的血清蛋白中还含有约12％白蛋白和9％其它γ-球蛋白。沉淀时IgG活性保持不变。     

黑果枸杞花青素提取物对大鼠急性痛风性关节炎的作用

为研究黑果枸杞花青素提取物(anthocyanin extract of Lycium ruthenicum Murr., AEL)对急性痛风性关节炎(acute gouty arthritis, AGA)大鼠的作用,将60只雄性SD大鼠,随机分为正常对照组、模型对照组、阳性对照组、AEL高剂量组(238.0mg/kg)和AEL低剂量组(59.5mg/kg),每组12只,分为2批,每批6只。第一批动物灌胃2周,第二批动物灌胃4周后,采用50mg/mL微晶型尿酸钠(microcrystalline sodium urate, MSU) 0.2mL注射到大鼠右踝关节诱导大鼠急性痛风性关节炎模型,评价AEL对AGA大鼠踝关节肿胀和跛行步态的改善效果。所有动物继续灌胃至5周,采用质量分数2.5%的氧嗪酸钾饲料喂食诱导高尿酸血症模型,测定造模2h、3h后大鼠的血清尿酸水平。研究发现,与模型对照组比较,灌胃2周,AEL高剂量能明显缓解大鼠造模6h后踝关节肿胀,改善跛行步态;灌胃4周,AEL高、低剂量均能明显缓解大鼠造模后6h、24h踝关节肿胀和改善造模6h后跛行步态,AEL高剂量还能明显改善造模24h后跛行步态;灌胃5周后,AEL高、低剂量均能明显抑制氧嗪酸钾导致的大鼠血清尿酸升高。结果表明,AEL能从抗炎和降尿酸两个方面对大鼠急性痛风性关节炎表现出明显改善作用。     

鸭血浆胆碱酯酶的分离纯化和性质的研究

将鸭血浆用0．2mol／L pH7．2磷酸盐缓冲溶液等体积稀释后，以硫酸铵为盐析剂进行二次盐析、再经DEAE-52离了交换层析和Sephadex G-200凝胶过滤层析对胆碱酯酶进行分离纯化，可获得电泳纯的胆碱酯酶，纯化倍数为278．5倍，酶活回收为17．8％。实验表明，该酶的最适温度为37℃，最适pH为7．8，有过量底物抑制现象。     

Inhibitory effects of flavonoid glycosides isolated from the peel of Japanese persimmon (Diospyros kaki Fuyu) on antigen-stimulated degranulation in rat basophilic leukaemia RBL-2H3 cells

We found that two distinct flavonoid glycosides isolated from the peel of Japanese persimmon (Diospyros kaki Fuyu), isoquercitrin (Isq) and hyperin (Hyp), are capable of inhibiting antigen-stimulated degranulation in rat basophilic leukaemia RBL-2H3 cells. In order to elucidate the underlying mechanisms, we examined effects of Isq and Hyp on cellular responses induced by antigen stimulation. Treatment with both Isq and Hyp markedly inhibited antigen-stimulated elevation of intracellular free Ca²⁺ concentration and reactive oxygen species (ROS). Isq and Hyp did not affect NADPH oxidase (NOX) activity, but they possessed DPPH radical-scavenging activity similar to that of epigallocatechin gallate, a potent anti-oxidant, Finally, Isq and Hyp showed little or no effects on Ag-stimulated Syk activation or phosphorylation of signalling molecules. These results indicate that inhibition of antigen-stimulated degranulation by Isq and Hyp is mainly due to suppression of intracellular Ca²⁺ elevation, which is caused by direct scavenging of ROS that are generated by NOX. Our findings suggest that Isq and Hyp, isolated from the peel of persimmon, would be beneficial for alleviating symptoms of type I allergy.     

南瓜籽油降脂模型血清脂肪酸的变化

为了筛选南瓜籽油降脂效果的生物标志物,将36只SPF级KM系雄性小鼠随机分为对照组、高脂组、南瓜籽油干预组。喂养4周后处死,使用气相色谱-质谱检测血清脂肪酸的种类与含量。结果表明,各组小鼠血清脂肪酸种类无差别;而脂肪酸C16∶1、C18∶1、C18∶2、C22∶6的含量变化显著(p0.05)。因此,小鼠血清脂肪酸C16∶1、C18∶1、C18∶2、C22∶6可做为南瓜籽油降脂的生物标志物。     

牛血清白蛋白与柚皮素复合物的非变性质谱研究

血清白蛋白是血液中最丰富的蛋白,研究其与药物的结合情况对了解药物在体内的运输和分布具有重要意义。本研究以柚皮素为模型药物,采用非变性质谱法研究牛血清白蛋白（BSA）与柚皮素的相互作用情况。结果表明,BSA与柚皮素形成了化学计量比为1∶1和1∶2的非共价复合物,二者亲和力较强（平衡解离常数Kd1=（7.82±0.03） μmol/L,Kd2=（9.63±0.02） μmol/L),结合速度快,5 min左右即可达到饱和。该方法具有操作简便、检测快速、样品消耗量小、无需标记等优点,可为其他药物与血清白蛋白的相互作用研究提供参考。