多肽和蛋白质的反相高效液相色谱研究--色谱行为的多样性

以Ｃ８柱为固定相,研究了微管结合蛋白２中两段重要肽段（肽１,肽２）和猪胰岛素在反相色谱上的保留行为。当以甲醇溶液为流动相时,猪胰岛素保留因子的对数值（ｌｎＫ’）随流动相有机溶剂体积分数（ψ）的变化呈现很好的线性关系。当以乙腈为流动相测定肽１的ｌｎＫ’随ψ变化关系时,所得结果显示ｉｎＫ’与ψ呈现良好的二次曲线关系。以乙腈为流动相测定肽１和肽２和Ｖａｎ’ｔ Ｈｏｆｆ曲线（ｌｎｋ’与１／Ｔ的关系图）时,     

Dispersive liquid–liquid microextraction of quinolones in porcine blood: Validation of a CE method using univariate calibration or multivariate curve resolution‐alternating least squares for overlapped peaks

In the previously published part of this study, we detailed a novel strategy based on dispersive liquid–liquid microextraction to extract and preconcentrate nine fluoroquinolones in porcine blood. Moreover, we presented the optimized experimental conditions to obtain complete CE separation between target analytes. Consequently, this second part reports the validation of the developed method to determine flumenique, difloxacin, enrofloxacin, marbofloxacin, ofloxacin, ciprofloxacin, through univariate calibration, and enoxacin, danofloxacin, and gatifloxacin through multivariate curve resolution analysis. The validation was performed according to FDA guidelines for bioanalytical assay procedures and the European Directive 2002/657 to demonstrate that the results are reliable. The method was applied for the determination of fluoroquinolones in real samples. Results indicated a high selectivity and excellent precision characteristics, with RSD less than 11.9% in the concentrations, in intra‐ and interassay precision studies. Linearity was proved for a range from 4.00 to 30.00 mg/L and the recovery has been investigated at four different fortification levels, from 89 to 113%. Several approaches found in the literature were used to determinate the LODs and LOQs. Though all strategies used were appropriate, we obtained different values when using different methods. Estimating the S/N ratio with the mean noise level in the migration time of each fluoroquinolones turned out as the best studied method for evaluating the LODs and LOQs, and the values were in a range of 1.55 to 4.55 mg/L and 5.17 to 9.62 mg/L, respectively.     

乳胶凝集法快速检测猪圆环病毒2型

发展了一种简单、快速、灵敏的乳胶凝集法用于猪圆环病毒2M的检测.合成了带有磺酸基的三元聚合物乳胶微球,通过静电相互作用,将猪圆环病毒2型单克隆抗体吸附到乳胶微球表面,形成乳胶抗体复合物诊断试剂.乳胶抗体复合物诊断试剂表面抗体与病毒表面抗原发生特异性反应,促使分散的乳胶微球凝集在一起,出现肉眼可见的凝集现象,而与去离子水...     

A Chemo-enzymatic Route for the Preparation of Chiral （S）-3-Hydroxy-3-phenylpropanoic Acid

（S）-3-Hydroxy-3-phenylpropanoic acid is a potential progenitor of optically pure tomoxetine hydrochlo- ride and fluoxetine hydrochloride which are currently available antidepressant drugs. We report here the chemical synthesis of racemic substrate （R,S）-ethyl 3-hydroxy-3-phenylpropanoate and enzymatic preparation of S-isomer of the substrate by employing Porcine pancreas lipase（PPL） as a biocatalyst. Optimum enzyme-catalyzed reaction con- ditions, such as the effects of the temperature, pH and solvents on conversion degree and enantiomeric excess, were studied. An optimal temperature of 35 ℃ and pH=7.5 are the best for the resolution of （R,S）-ethyl 3-hydroxy-3- pheylpropanoate by PPL when 0.1 mol/L phosphate buffer solution acts as a medium. This work provides a practi- cally chemo-enzvmatic oreoaration of chiral β-hvdroxv acid by PPL.     

低氧亲和力血红蛋白类氧载体的制备及大鼠动脉血压响应

氧亲和力是血红蛋白氧载体非常重要的参数之一,但其高低还没有统一的认识,有一种理论认为低氧亲和力是造成高血压的原因。为了进一步研究氧亲和力与血压之间的关系,本文制备了两种低氧亲和力的血红蛋白氧载体。用高碘酸钠氧化棉子糖（高碘酸钠：棉籽糖=6：1,摩尔比）,得到氧化均一的开环棉子糖;以其作为交联剂聚合脱氧猪血红蛋白,在聚合1 h得到了低氧亲和力（P50 = 43.1 torr）主要为分子内交联的64 kDa的血红蛋白,在聚合2 4 h得到了低氧亲和力（P50 = 51.5 torr）平均分子量为600 kDa的聚合血红蛋白;分别进行大鼠50%等容量换血实验,前者显著引起血压升高而后者血压平稳,证实高血压主要和64 kDa血红蛋白有关,低氧亲和力不是造成高血压的主要原因。     

Characterization of Titanium Dioxide Nanoparticles on Porcine Skin by Raman Microscopy

Titanium dioxide nanoparticles are a key ingredient in sunscreen products for efficiently blocking ultraviolet irradiation on the skin. Lately, there have been concerns about their cytotoxicity, oxidative stress, and DNA damage to skin cells. One way to minimize the potential side effects is to wash away the nanoparticles from skin. However, the effectiveness of this strategy has not been evaluated, which is partially due to the lack of a convenient technology for skin analysis. Herein, a portable Raman microscope was shown for the first time to rapidly reveal and quantify titanium dioxide nanoparticle residue on the skin after cleaning. By using porcine skin as an example, cleaning with the detergent was determined as the fastest and most efficient way to remove the nanoparticles from the skin.     

Determination of dimetridazole and metronidazole in poultry and porcine tissues by gas chromatography-electron capture negative ionization mass spectrometry

A sensitive and selective method using gas chromatography-electron capture negative ionization mass spectrometry (GC-ECNI-MS) for analysis of dimetridazole (DMZ) and metronidazole (MNZ) in poultry muscles, porcine kidney and liver, and chicken liver, was developed and validated for the purpose of food surveillance testing of the residues of these two nitroimidazoles in various types of animal tissues in the Hong Kong Special Administrative Region. Before homogenization and extraction with toluene, [2H₃]dimetridazole-(DMZ-d³) and secnidazole (SNZ) were added to tissue samples as internal standards. The organic extracts were mixed with n-hexane and subject to solid-phase extraction cleanup by amine extraction columns. MNZ and SNZ were derivatized with BSA prior to GC-ECNI-MS determination. Good recovery and precision were obtained and the limit of detection was below parts per billion levels for poultry and porcine tissues. The method could also be applied for the detection of the hydroxylated metabolite of DMZ.     

STUDY ON IMMOBILIZED PORCINE PANCREATIC LIPASE CATALYZING TRANSESTERIFICATION BETWEEN METHYL－BUTYRATE AND 1－BUTANOL IN NONAQUEOUS SYSTEMS

ＳＴＵＤＹＯＮＩＭＭＯＢＩＬＩＺＥＤＰＯＲＣＩＮＥＰＡＮＣＲＥＡＴＩＣＬＩＰＡＳＥＣＡＴＡＬＹＺＩＮＧＴＲＡＮＳＥＳＴＥＲＩＦＩＣＡＴＩＯＮＢＥＴＷＥＥＮＭＥＴＨＹＬ－ＢＵＴＹＲＡＴＥＡＮＤ１－ＢＵＴＡＮＯＬＩＮＮＯＮＡＱＵＥＯＵＳＳＹＳＴＥＭＳＸｉ...     

Acyclic phenylalkanediols as substrates for the study of enzyme recognition. Regioselective acylation by porcine pancreatic lipase: a structural hypothesis for the enzymatic selectivity

The regioselective acylation of phenylalkanediols catalysed by porcine pancreatic lipase (PPL) was the reaction used for modelling different areas in the active site of the enzyme. With this aim, different racemic or prochiral (1,n)-diols, with n ranging from 2 to 6 were resolved via transesterification with vinyl acetate, and the results were explained according to microcrystalline enzyme structure. Thus, we describe a logical model for explaining the enzyme regio and stereoselectivity, based on three residues of the active site (Ser153, Phe216 and His264) which turned out to be crucial for the substrate binding and transformation.     

Novel Applications of Raney Nickel/Isopropanol: Efficient System for the Reduction of Organic Compounds

Catalytic hydrogenation of various organic substrates with Raney nickel in isopropanol proceeds under mild conditions of temperature and pressure. Comparison with other catalysts systems evidenced the superiority of Raney nickel/isopropanol.