佛波酯能改变细胞表面糖蛋白N－糖链的结构

利用标记Ｎ－糖链的凝集素亲和层析法研究了佛波醇肉桂酸乙酸酯（ＰＭＡ）对人肝癌细胞ＳＭＭＣ－７７２１表面糖蛋白上Ｎ－糖链结构的影响,发现１００ｎｍｏｌ／Ｌ的ＰＭＡ处理５天后,可使细胞表面Ｎ－糖链中高甘露糖型和杂合型以及四天线、Ｃ２Ｃ２,６三天线复杂型的比例增高,而二天线复杂型降低。此结果与我们曾报道的视黄酸（ＲＡ）和双丁配环磷酸腺苷（ｄｂ－ｃＡＭＰ）对该细胞表面Ｎ－糖链的影响相反。因ＲＡ和ｄｂ－ｃＡＭＰ是ＳＭＭＣ－７７２１细胞的分化诱导剂,可抑制细胞生长;而ＰＭＡ是该细胞的增殖促进剂,故细胞表面Ｎ－糖链的变化与细胞的分化和增殖密切相关。     

气相色谱法测定梭菌酸性代谢产物

本文报告用气相色谱法对８株梭菌代谢产物中的挥发性及非挥发性有机酸进行测定。采用程序升温方法,样品中各种成份分离较好,所需样品量少,操作方便,样品分析结果与标准菌株及文献对照比较,为梭菌的分类鉴定提供了实验依据。     

O_(139)霍乱弧菌流行病学

霍乱流行史上,七次世界性大流行都是由Ｏ１群霍乱弧菌所引起,但从１９９２年１０月至１９９３年４月,印度次大陆却爆发了由非－Ｏ１霍乱弧菌Ｏ（１３９）血清型引起的霍乱样病大流行,印度及孟加拉相继报道了引起全国流行的霍乱样急性腹泻。从流行区病人分离的菌株不被Ｏ１群霍乱弧菌抗血清所凝集,也不被已知的１３７个血清型非－Ｏ１霍乱弧菌抗血清所凝集,因此将这一引起霍乱样病的非－Ｏ１霍乱弧菌定名为Ｏ（１３９）。本文就引起霍乱样病流行的Ｏ（１３９）霍乱弧菌的来源,本次流行概况,流行特点,Ｏ（１３９）流行株的特性及流行预测做一简要概述以提醒国内霍乱流行病学工作者的重视,对这一霍乱新菌型有所认识,密切监视Ｏ（１３９）菌型的流行动态及传播趋势,做好应有的防疫工作。     

Evidence for the Presence of "Metabolic Sterols" in Pneumocystis: Identification and Initial Characterization of Pneumocystis carinii Sterols

Mixed life cycle stages of rat-derived Pneumocystis carinii were isolated from host lungs and their sterols were compared with those present in lungs from normal and immunosuppressed uninfected rats. Gas-liquid chromatography consistently detected, resolved, and quantified 9, 10, and 20 sterol components in the total nonsaponifiable neutral lipid fraction of lungs from normal rats, lungs from immunosuppressed uninfected rats, and P. carinii preparations, respectively. In all samples, cholesterol was the most abundant sterol present, comprising 97%, 93%, and 78% of total sterols in lungs from normal rats, lungs from immunosuppressed uninfected rats, and P. carinii , respectively. Tentative identifications of several rat lung and P. carinii minor sterols were made based on gas-liquid chromatogram retention times and fragmentation patterns from mass spectral analyses. Campesterol (ergost-5-en-3-ol), cholest-5-en-3-one, and β -sitosterol (stigmast-5-en-3-ol) were among the minor components present in both types of lung controls, and were also components of P. carinii sterols. In contrast to lung controls, the sterols of P. carinii were enriched in C₂₈ and C₂₉ sterols with one or two double bonds, and a hydroxyl group at C-3 (ergost-5-en-3-ol, ergost-7-en-3-ol, ergosta-dien-3-ol, stigmast-5-en-3-ol, stigmast-7-en-3-ol and stigmasta-dien-3-ol). Steryl esters of P. carinii , probably stored in cytoplasmic lipid droplets, were dominated by those present in the host lung. In separate studies. 3-hydroxy-3-methylglutaryl coenzyme A activity, a key enzyme in the regulation of sterol biosynthesis, was detected in purified P. carinii preparations and incorporation of radiolabeled squalene and mevalonate was observed. Together, these results suggest that the parasite readily takes up and incorporates host sterols, and that the organism synthesizes some of its own "metabolic sterols"     

High-temperature gas chromatography and gas chromatography-mass spectrometry of glycoprotein and glycosphingolipid oligosaccharides

High-temperature gas chromatography and gas chromatography-inass spectrometry for the analyses of oligosaccharides derived from glycoproteins or glycosphingolipids has been developed. Pcrmethylatcd oligosaccharides with up to about 12 sugar residues and masses up to 2500 Daltons can be analyzed. This approach is discussed and exemplified.     

Rapid purification of DesPro(2)-Val15-Leu17-aprotinin from the culture broth of a recombinant Saccharomyces cerevisiae

A rapid two-step procedure has been developed for the purification of Despro(2)-Val15-Leu17-aprotinin from the culture supernatant of a recombinant yeast by affinity and ion-exchange chromatography. DesPro(2)-Val15-Leu17-aprotinin was purified to homogeneity, as demonstrated by dodecylsulfate gel electrophoresis and analysis of the N-terminal amino acid sequence. (c) 1993 John Wiley & Sons, Inc.     

Application of continuous zone electrophoresis to preparative separation of proteins

A comprehensive study of the application of continuous zone electrophoresis to preparative separation of proteins in free solution is presented. First, the influence of electric field strength, buffer residence time in the chamber, sample flow rate, and sample concentration on separation resolution and throughput were studied. Using multiple injections of sample into the electrophoresis chamber, a throughput of 500 mg protein/h was achieved for partially purified model proteins. Experiments on Escherichia coli crude extracts yielded a fivefold purification of beta-galactosidase along with a simultaneous separation of proteins from cell debris in a single step. Experiments correlating the electrophoretic mobility in continuous electrophoresis with the elution behavior in ion-exchange chromatography were performed on more than a dozen proteins which conclusively showed that separation of proteins in continuous zone electrophoresis is governed by net surface charge. Based on these results, the fraction numbers in which the proteins eluted could be correctly predicted. Proteins and enzymes with differences >0.5 M elution molarities in ion-exchange chromatography were separated by continuous zone electrophoresis on a preparative scale (mg/h or g/h) with >90% recovery. This corresponds to a preparative scale separation of proteins and enzymes which differ in apparent electrophoretic mobility by only 0.70 x 10(-5) cm(2)/V . s. (c) 1993 John Wiley & Sons, Inc.     

Immunoaffinity co-purification of cytokinins and analysis by high-performance liquid chromatography with ultraviolet-spectrum detection

A rapid methodology for the simultaneous analysis of a large number of cytokinins is presented. The cross-reactivity of a mixture of polyclonal antibodies against zeatin riboside and isopentenyladenosine was exploited in a protocol that can be used for immunoaffinity purification of 23 additional cytokinins. Ligands include the cytokinin bases zeatin, dihydrozeatin, isopentenyladenine, benzyl-adenine and kinetin, and their corresponding nucleoside, nucleoside-5′-monophosphate, and 9-glucoside derivatives, as well as cis-zeatin, cis-zeatin riboside, the 2-methylthiol derivatives of isopentenyladenosine and zeatin riboside, and benzyl-adenine-3-glucoside. Mixtures of cytokinins could be retained with high recoveries of all the components. Immunoaffinity purification of extracts of Arabidopsis thaliana (L.) Heynh. and Solarium tuberosum L. gave fractions clean enough, as verified by gas chromatographymass spectrometry (GC-MS), to allow analysis of endogenous cytokinins using a single high-performance liquid chromatography (HPLC) step with on-line UV-spectrum detection. The detection limit was 4–6 pmol. The procedure described forms a routine assaying technique that is faster and simpler, yet yields better qualitative and quantitative information than the commonly used procedure of immunoassaying of HPLC fractions.     

大鼠脑突触质膜糖皮质激素受体的纯化

本文利用抗大鼠肝细胞内糖皮质激素受体的单克隆抗体制备的免疫亲和层析柱,将大鼠脑突触质膜糖皮质激素受体纯化了约1150倍,SDS聚丙烯酰胺簿层梯度凝胶电泳显示,在约67kD处有一较明显的染色条带。     

平菇子实体钙调素的分离纯化及其与猪脑钙调素的生物活性比较

平菇萃取液经酸性沉淀、热变性、Phenyl-Sepharose CL-4B疏水亲和层析和DEAE-Cellulose 52离子交換层析分冉出了电泳纯的真菌钙调素。在比较钙调素对磷酸二酯酶活化的能力和ELISA实验的免疫亲和力对发现,平菇钙调素与猪脑钙调素的生物活性有较大差异,提示在钙调素定量测定中有必要考虑到标准钙调素与样品钙调素之间的同源性差异。