稀土在鼠肝中的物种分布

采用 ICP-MS、微量蛋白层析分离技术 ,研究了长时间、低剂量混合稀土及短时间、高剂量硝酸镧分别对大鼠及小鼠作用后 ,稀土在鼠肝中的代谢累积及其物种分布 .结果表明 ,鼠肝中各稀土含量随给药剂量的增加而增大 ,其累积速度大小顺序为 La>Ce>Nd>Pr;经柱层析分离未得到与稀土特异结合的鼠肝蛋白 ;稀土可与多种鼠肝蛋白 (包括多种重要的酶 )结合 ,在一定条件下 ,稀土与其结合蛋白可发生解离     

Alkylation of benzene with 1-hexene in acidic ionic liquid systems: Et3NHCl-FeCl3and Et3NHCl-AlCl3ionic liquids

Summary The alkylation of benzene with 1-hexene has been investigated in different triethylamine hydrochloride-ferric chloride (Et₃NHCl-FeCl₃) and triethylamine hydrochloride-aluminium chloride (Et₃NHCl-AlCl₃) ionic liquids. Both high catalyst activity and monoalkylation selectivity were observed for these two type of ionic liquids. Systems prepared by modification with HCl in Et₃NHCl-FeCl₃ionic liquids prove to be very suitable solvents and catalysts for the reaction. When employing Et₃NHCl-AlCl₃ionic liquids as catalysts, the reaction takes place in biphasic mode with facile catalyst separation and catalyst recycling.     

偶合反应化学发光法测定痕量银的研究

本文报道了Ａｇ（Ⅰ）催化ｏ－ｐｈｅｎ和Ｋ４Ｆｅ（ＣＮ）６的配位体取代反应与Ｌｕｍｉｎｏｌ－Ｃｕ（ＣＮ）２－４的化学发光反应偶合测定痕量银的方法．方法的线性浓度范围为１×１０－１１～１×１０－７ｇ／ｍＬＡｇ，检出限为４×１０－１２ｇ／ｍＬＡｇ，用于水样分析，结果较为满意     

Concise Synthesis and Antimicrobial Activities of New Substituted 5‐Isoxazolpenicillins

The synthesis of a series of new 5‐isoxazolpenicillins is described, which were obtained by coupling substituted isoxazoles with 6‐APA. Concise large‐scale synthesis of 3,5‐disubstituted isoxazoles by 1,3‐dipolar cycloaddition using copper(I) as catalyst was also investigated. Representative compounds were assayed for antimicrobial activities, showing satisfactory antimicrobial activities against Gram‐negative bacteria.     

Structural mining: self-consistent design on flexible protein-peptide docking and transferable binding affinity potential

A flexible protein-peptide docking method has been designed to consider not only ligand flexibility but also the flexibility of the protein. The method is based on a Monte Carlo annealing process. Simulations with a distance root-mean-square (dRMS) virtual energy function revealed that the flexibility of protein side chains was as important as ligand flexibility for successful protein-peptide docking. On the basis of mean field theory, a transferable potential was designed to evaluate distance-dependent protein-ligand interactions and atomic solvation energies. The potential parameters were developed using a self-consistent process based on only 10 known complex structures. The effectiveness of each intermediate potential was judged on the basis of a Z score, approximating the gap between the energy of the native complex and the average energy of a decoy set. The Z score was determined using experimentally determined native structures and decoys generated by docking with the intermediate potentials. Using 6600 generated decoys and the Z score optimization criterion proposed in this work, the developed potential yielded an acceptable correlation of R(2) = 0.77, with binding free energies determined for known MHC I complexes (Class I Major Histocompatibility protein HLA-A(*)0201) which were not present in the training set. Test docking on 25 complexes further revealed a significant correlation between energy and dRMS, important for identifying native-like conformations. The near-native structures always belonged to one of the conformational classes with lower predicted binding energy. The lowest energy docked conformations are generally associated with near-native conformations, less than 3.0 Angstrom dRMS (and in many cases less than 1.0 Angstrom) from the experimentally determined structures.     

柠檬酸铝/聚丙烯酰胺胶态分散凝胶反应动力学和机理的研究

采用粘度法研究了柠檬酸铝（AlCit)与部分水解取丙烯酰胺（HPAM）胶态分散凝胶体系的反应动力学。结果表明，胶态分散凝胶体系的交联反应是一级反应。并推导出胶态分散凝胶体系的反应动力学方程。     

Palladium‐Catalyzed Three‐Component Coupling Reaction of Allyl Carboxylates,Norbornenes and Diboronates Involving Sequential Olefins Insertion and Borylation Reaction

An efficient Pd‐catalyzed three‐component coupling reaction of allyl carboxylates, norbornenes and diboronates is described, which allows efficient assembly of C(sp³)—C(sp³) and C(sp³)—B bonds in a single process. Moreover, this approach shows advantages of good chemo‐ and regioselectivity, as well as good substrates suitability.     

Intriguing self-assembly of large granules of F-actin facilitated by gelsolin and alpha-actinin

We report microscopic observations and a structural determination of actin granules self-assembled in concentrated solutions of actin filaments (F-actin). Optical microscopy shows reproducible formation of numerous and stable granules of densely packed F-actin of variable sizes on the order of 10 microm. These granules coexist with a uniform network of F-actin of a lower concentration. The microscopic segregation of F-actin into two distinct states is assisted by an actin cross-linking protein, alpha-actinin. The rapid on and off rates and temperature sensitivity of the alpha-actinin/F-actin interaction facilitate the formation of multi-micrometer-sized granules of well-defined shapes. Additional physical factors such as the excluded volume effect and the minimization of surface energy act in concert with the specific molecular interactions to define the intriguing granular formation. Both the biochemical specificity of alpha-actinin and the thermodynamics of phase transitions are required for understanding such large scale self-assembly.     

Novel 99mTc labeled σ receptor ligand as a potential tumor imaging agent

A novel ^99mTc labeled complex, [N-[2-((2-oxo-2-(4-(3-phenylpropyl)piperazin-1-yl)ethyl) (2-mercaptoethyl)amino)acetyl]-2-aminoethanethiolato]Technetium(V) oxide (PPPE-MAMA’-^99mTcO) ([ ^99m Tc]-2) has been designed and prepared based on the integrated approach. The corresponding rhenium complex (PPPE-MAMA’-ReO)(Re-2) has been prepared and characterized. In vitro competition binding assays show moderate affinity of Re-2 towards σ₁ and σ₂ receptors with K _i values of 8.67 ± 0.07 and 5.71 ± 1.88 μmol, respectively. Planar images obtained at 0.5 h, 4 h, 20 h after i.v. injection indicate the accumulation of [ ^99m Tc]-2 in MCF-7 human breast tumor bearing mice at 20 h. Furthermore, the accumulation of [ ^99m Tc]-2 has been inhibited at 20 h after co-injection of [ ^99m Tc]-2 plus haloperidol (1 mg/kg). Biodistribution studies of [ ^99m Tc]-2 display an in vivo tumor uptake of 0.14% ± 0.01% ID/g at 24 h post i.v. injection with a tumor/muscle ratio of 6.02 ± 0.87. The above results suggest that [ ^99m Tc]-2, derived from a previously published lead compound, retains certain tumor uptake and affinity for σ receptors. [ ^99m Tc]-2 may be used as a basis for further structural modifications to develop tumor imaging agents with high affinity for σ receptors.