Synthesis of Z and E-(2',5'-dimethoxyphenyl)-methylene-butyrolactones

Pseudotaxlactone was isolated by Zhang1 from Taxaceae plant pseudotaxus chienii(Cheng) Cheng. It's structure was tentatively assigned as 5-(4-hydroxy-3,5- 20%(Z,9), 4%(E,8).The intermediate 7 was synthesized using 2,5-dimethoxy-phenyl acetic acid as astarting material. However, cyclization reaction gave Z-(2,5-dimethoxy-phenyl)methylene-butyrolactone 9 (20%) and E-(2,5-dimethoxy-phenyl)-methylelactone 8 (4%), instead of the desired counterpart with endocyclic unsaturation. Thereaction of t…     

Volumetric method for following the rate of intercalation of liquid molecular guests into layered hosts

A new experimental method is suggested for the kinetic measurements of intercalation reactions in systems formed by a polycrystalline layered host and a liquid molecular guest. The method is based on the fact that the molecular guest decreases its molar volume on entering the space between the host layers. Hence the volume of the system in which an intercalation process takes place is measurably decreased. The time course of the intercalation process can thus be monitored by measuring the volume change of the system. The method has been used to obtain kinetic data about heterogeneous intercalations of some liquid aliphatic compounds into layered structures of anhydrous vanadyl phosphate and sulfate.     

盐酸在硫酸镍水溶液中的活度系数

以标准氢电极和银-氯化银电极组成无液接电池,研究HCl-NiSO4-H2O体系.在恒定溶液总离子强度I=0.4、0.6、0.8、1.0、1.5 、2.0 mol•kg－1, NiSO4在溶液中的离子强度分数yB=0.00、0.10、0.20、0.30、0.50、0 .70的条件下,在278.15～323.15 K温度范围内测定电池: Pt, H2(101.325 kPa)│HCl(mA), NiSO4(mB), H2O│AgCl-Ag 的电动势.根据测得的电动势数据,考虑到体系存在硫酸的二级解离,应用数学迭代方法确定平衡体系氢离子的浓度,进而计算了混合溶液中HCl的活度系数γA.结果表明,在溶液中总离子强度保持恒定时, HCl 的活度系数服从Harned规则.     

Polyacrylamide gel electrophoresis of fluorophore-labeled hyaluronan and chondroitin sulfate disaccharides: application to the analysis in cells and tissues

This report describes a new formulation of polyacrylamide gel electrophoresis of fluorophore-labeled saccharides (PAGEFS) for the analysis of hyaluronan (HA) and chondroitin sulfate (CS) Delta-disaccharides. PAGEFS relies on derivatization of reducing ends of HA- and the variously sulfated CS-derived Delta-disaccharides with 2-aminoacridone (AMAC), followed by electrophoresis under optimized buffer conditions (Tris-borate and Tris-HCl) and on polyacrylamide gels (25% T/3.75% C). The method was applied to the analysis of glycosaminoglycans (GAGs) from the human umbilical cord tissue and GAGs isolated from human aortic smooth muscle cell cultures. The obtained results were in agreement with those obtained after an analysis with high-performance liquid chromatography (HPLC). On the basis of these results, PAGEFS is a rapid and sensitive method for the analysis of the total amount of HA- and CS-derived disaccharides, as it allows analyzing 20 samples in minigels in one run and provides quantitation with relatively high sensitivity (less than 25 pmol per disaccharide). In addition, PAGEFS overcomes the lack of commercial gels described previously for the separation of AMAC-labeled disaccharides. Therefore, the method proposed here is an economic and useful tool for a fast screening of GAGs in biological samples, particularly when a high number of samples should be analyzed.     

Fluorinated peptidomimetics: synthesis, conformational and biological features

Peptides modified with fluoroalkyl functions in key backbone positions have been scarcely studied so far. Thus, little is known about their synthesis, their structural and physico-chemical properties, and their biological features. Our interest in this field of research led to the development of stereocontrolled synthetic protocols, both in solution and in solid phase, for many different fluoroalkyl peptidomimetics, some of which are overviewed in this paper: (a) ψ[CH(CF₃)NH]-peptide mimics holding a great potential as hybrids between natural peptides and hydrolytic transition state analogs; (b) trifluoromethyl (Tfm) malic peptidomimetics as micromolar inhibitors of some matrix metalloproteinases; (c) bis-Tfm analogs of Pepstatin A, that are nanomolar and selective inhibitors of the protozoal aspartyl protease Plasmepsin II.     

十二烷基硫酸钠/苯甲醇/水微乳液中吩噻嗪对蒽的荧光猝灭

吩噻嗪与蒽之间可以发生光诱导单电子转移反应. 用荧光光谱仪研究了十二烷基硫酸钠(SDS) / 苯甲醇(BA) / 水微乳液中吩噻嗪对蒽的荧光猝灭.结果表明，在W/O微乳液中，蒽位于苯甲醇连续相，吩噻嗪位于膜相，猝灭反应发生于膜相；而在O/W微乳液中，蒽既可位于油核中，也可位于膜相，吩噻嗪位于膜相，猝灭反应亦发生于膜相.     

硫酸锌与α-氨基酸的相化学及其新相的合成和表征

α 氨基酸锌作为添加剂在药物、食品和化妆品等方面都有广阔的应用前景[1,2 ] 。有关氨基酸锌的合成方法前文[3] 已述及。而用相平衡方法研究锌盐与氨基酸的配合行为的相化学[4] ,对新型配合物 ,特别是固液异成分化合物的合成有指导意义。本文对ＺｎＳＯ4与人体必需而非自生的Ｌ 亮氨酸 (Ｌ Ｌｅｕ)、Ｌ 色氨酸 (Ｌ Ｔｒｙ)、Ｌ 苏氨酸 (Ｌ Ｔｈｒ)和Ｌ 缬氨酸 (Ｌ Ｖａｌ)在水中的等温溶度性质进行了研究 ,构制了其相图 ,讨论了未形成化合物的原因。合成了未见报道的Ｚｎ(Ｌｅｕ)ＳＯ4·0 .5Ｈ2 Ｏ ,Ｚｎ(Ｖａｌ)ＳＯ4·Ｈ2 Ｏ和固态配合物…     

The Electrooxidation of Tetracycline at Acetylene Black Electrode in the Presence of Sodium Dodecyl Sulfate

The electrooxidation of tetracycline (TC) at acetylene black electrode has been studied in the presence of sodium dodecyl sulfate (SDS). Tetracycline (TC) exhibited very sensitive oxidation peak in this system. The peak current was proportional to TC concentration, and the detection limit was 1.2×10-8 mol/L. The system was used to the determination of TC in Pharmaceuticals.     

血清中硫脂质的提纯及其结构分析

应用离子交换及硅胶柱色谱法分离提纯血清中酸性脂质,并采用薄层色谱法(TLC)、TLC免疫染色法、质谱法及溶化分解等方法分析血清中硫脂质的种类及结构。实验确定了样品的提纯体系,证实胆固醇硫酸及脑硫脂是血清中的主要硫脂质。     

Analysis of proteins stained by Alexa dyes

Alexa dye staining of proteins is used for the fluorescence microscopy of single particles that are sometimes multimolecular protein complexes. To characterize the staining, post-staining determination must be made of which protein(s) in a complex have been Alexa-stained. The present communication describes the use of sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE) for performing this determination. The Alexa-stained proteins are observed directly in gels by illumination with an ultraviolet transilluminator. The test multimolecular particle is bacteriophage T7. The protein capsid of T7 is a multimolecular complex that has both external and internal proteins. SDS-PAGE of Alexa-stained bacteriophage T7 produces fluorescent capsid proteins each of which usually comigrates with an unstained protein. However, one Alexa-induced modification of protein migration was observed by SDS-PAGE. Mass spectrometry shows that the protein with modified migration is the major protein of the outer shell of the T7 capsid. The procedures used are generally applicable. The distribution of Alexa staining among T7 capsid proteins depends on the size of the dye molecule used. The larger the dye molecule is, the greater the preference for external proteins.