Occurrence of Polypeptides in Other Organisms Cross-reacting with Antibodies Against A. Xylinum Cellulose Synthase

Antibodies (anti-83 and anti-93) against the cellulose synthase complex from A. xylinum ATCC 53582 have been employed to study the evolutionary conservation of this enzyme complex among various A. xylinum strains, selected species of other cellulose- producing bacteria, algae, and vascular plants. Of the 18 A. xylinum strains examined, the 83 Kd polypeptide clearly is detected only in 4 strains while the 93 Kd polypeptide is observed in all 18 strains. Assuming that the revised acsAB gene (Saxena et al., 1994) encoding the 83 and 93 Kd polypeptides as a single polypeptide holds true for all A. xylinum strains, it is proposed that the cellulose synthase is conserved in A. xylinum but with varying degrees of homology. An unknown regulatory mechanism causing the degradation of the 83 Kd polypeptide in response to agitated culturing conditions has been suggested to explain the absence of the 83 Kd polypeptide in most of the Acetobacter strains examined. A. xylinum cellulose synthase appears to be conserved in phylogenetically related Rhizobium and Agrobacterium species, but not in algae and plants.     

稀土等离子与铁生物调控

本文在简介转铁蛋白、转铁蛋白受体的铁（Ⅲ）调控作用研究进展的基础上,综述了稀土离子、镓与转铁蛋白的作用及稀土离子、镓代谢与铁（Ⅲ）调控系统的关系。     

Alternative Representations of the Correlation Energy in Density‐Functional Theory: A Kinetic‐Energy Based Adiabatic Connection

The adiabatic‐connection framework has been widely used to explore the properties of the correlation energy in density‐functional theory. The integrand in this formula may be expressed in terms of the electron–electron interactions directly, involving intrinsically two‐particle expectation values. Alternatively, it may be expressed in terms of the kinetic energy, involving only one‐particle quantities. In this work, we explore this alternative representation for the correlation energy and highlight some of its potential for the construction of new density functional approximations. The kinetic‐energy based integrand is effective in concentrating static correlation effects to the low interaction strength regime and approaches zero asymptotically, offering interesting new possibilities for modeling the correlation energy in density‐functional theory     

The Total Synthesis of the Bioactive Natural Product Plantazolicin A and Its Biosynthetic Precursor Plantazolicin B

Herein, we describe our full investigations into the synthesis of the peptide‐derived natural product plantazolicin A, a compound that demonstrates promising selective activity against the causative agent of anthrax toxicity, and its biosynthetic precursor plantazolicin B. This report particularly focuses on the challenging preparation of the arginine containing thiazole fragment, including the development of a robust, high yielding procedure that avoids the use of sulfurating agents. Extensive studies on the design of a coherent protecting group strategy and the establishment of a step‐efficient dicyclization/oxidation approach allowed high levels of convergence for the construction of the oxazole fragments. This has led to a unified, highly convergent synthesis for both plantazolicin A and B.     

Novel Product and Its Derivatives from the Reaction of Lappaconitine with HIO_4

Lappaconitine l, a bisnorditerpenoid alkaloid, was isolated from many plants ofAconitum and Delphinium species such as A. barbatum var. puberulum, A.sinomontanuml' 2. It is now used in the clinical practice as an analgesic in China', andantiarrhythmic drugs in Uzbekistan4' 5. In our attempts to prepare the 10-oxygenatedderivatives by treating lappaconitine I with HIO. followed by bromination, unexpectedby-products were obtained in modest yields. This communication described the isolationan…     

Correlation of the Stretching Vibration Frequencies of EX n Diatomic Compounds with Each Other and with Structural and Thermodynamic Characteristics

A correlation was revealed between stretching vibration frequncies, internuclear distances, bondangles, thermodynamic parameters for EX _n compounds in which elements E belong to the same group ofthe periodic table.     

The alkoxide sol–gel process in the calcium phosphate system and its applications†

A single calcium glycolate was synthesized. The alkoxide was stable under ambient atmosphere. The calcium glycolate, phosphoric acid and P(OH) _x (OEt)_{3− x} were used as the precursors. Acetic acid was used as a reagent to modify the calcium glycolate and to change the acidity of the mixtures of the precursors. Mixtures of the calcium glycolate and phosphoric acid in a Ca/P ratio of 1.67 showed unusual sol–gel behavior. A transparent gel could be formed depending on the content of acetic acid and the extent of stirring. The behavior is attributed to a high viscosity and a large molecular size of the ethylene glycol solvent, leading to a strong dependence of the reactions in the mixtures on the diffusion process, greatly affected by stirring. When the mixtures of the calcium glycolate and PO(OH) _x (OEt) _{3− x} contained acetic acid at an acetic acid/Ca ratio of 3, stable alkoxide solutions with Ca/P ratios of 1.0, 1.5 and 1.67 could be formed. Different calcium phosphate compounds and hydroxyapatite coatings on alumina substrates could easily be formed from the alkoxide solutions. The chemical homogeneity provided by the alkoxide route leads to easy formation of the required products. Copyright © 1999 John Wiley & Sons, Ltd.     

Solubility Parameter of Gatifloxacin and Its Correlation with Antibacterial Activity

The solubility parameter of gatifloxacin was calculated theoretically by Fedors’ method and also determined experimentally using the standard solubility method. The molar volume of gatifloxacin was determined experimentally by the flotation method. Three solvents, ethyl acetate, propylene glycol and water were used to prepare nine binary mixtures having different solubility parameter values varying from 8.9 to 23.4 H. The δ ₂ solubility parameter of gatifloxacin was found to be 12.4 H. The cumulative transport of gatifloxacin from the binary solvent mixtures (ethyl acetate–propylene glycol and propylene glycol–water) exhibited an inverse parabolic relationship to the solubility parameter of the solvent mixtures. Transport studies revealed that the extent of gatifloxacin rejection from solvent mixtures was dependent on its solubility parameter and system composition. In the selected organisms (bacteria), a minimum zone of inhibition was observed in a solvent mixture having the solubility parameter nearest to the solubility parameter of gatifloxacin. Two models were employed for the evaluation of the antibacterial activity of gatifloxacin in binary mixtures.     

上转换荧光响应性复合纳米凝胶的制备及荧光能量传递行为

采用水热法合成NaYF₄∶Yb³⁺,Er³⁺稀土纳米晶, 再经3-苄基三硫代碳酸酯基丙酸(BSPA)修饰, 制得功能化纳米晶体; 以罗丹明6G(R6G)为母体荧光染料, 经一系列反应合成了乙烯基功能化单体罗丹明6G酰基邻羧基苯甲肼腙(R6GHA); 将功能化纳米晶体与R6GHA构成荧光共振能量传递(FRET)的“给体/受体”对, 通过可逆加成断裂链转移(RAFT)聚合和“点击化学”反应, 合成具有多重响应性复合荧光纳米凝胶NaYF₄∶Yb³⁺,Er³⁺/PNIPAm-co-R6GHA. 采用TEM, XRD, FTIR和DSC对产物的微观结构进行了表征; 采用上转换荧光光谱(PL)研究了该复合纳米凝胶对pH值、 环境温度和不同金属离子的荧光响应行为, 并对相关机理进行了探讨. 结果表明, 环境温度变化对复合纳米凝胶的荧光发射具有显著影响, 且该复合纳米凝胶对Hg²⁺具有选择性荧光响应; 在H⁺或Hg²⁺作用下, 复合纳米凝胶中纳米晶和R6GHA之间会发生荧光共振能量传递; 通过纳米凝胶中纳米晶与R6GHA特征荧光发射峰比率的变化, 实现对Hg²⁺的检测.     

赖氨酸与香草醛反应产物的极谱波特征及其分析应用

研究了赖氨酸与香草醛反应产物的极谱波特征并建立了赖氨酸的分析方法。在0.1mol/L磷酸盐缓冲溶液中赖氨酸与香草醛反应的产物于－1.16V产生灵敏的极谱波,赖氨酸浓度在5×10     

天然产物骆驼宁碱A及其衍生物的合成研究进展

骆驼宁碱A是从骆驼蒿中分离出来的喹唑啉酮类生物碱, 骆驼蒿在中国民间用来治疗风湿病、炎症、脓肿及其他疾病. 由于骆驼宁碱A的药理活性, 有关其合成方法受到了关注. 综述了该化合物的合成方法, 根据闭环方式的不同把合成方法分为六大类, 大部分方法都围绕中间体喹啉吡咯烷酮的合成, 一般步骤较长, 产率过低, 虽然有的路线步骤短, 产率高, 但原料不易得到. 因此, 经济的产业化方法还有待进一步研究.     

Study on the Correlation between the Protein Profile of Lupin Milk and Its Cheese Production Compared with Cow’s Milk

Australian sweet lupin, the largest legume crop grown in Western Australia, is receiving global attention from the producers of new foods. To understand the effect of protein on cheese yield, lupin milk proteins were separated from the first, second, and third filtrations by cheesecloths. However, proteins from the first and second were analyzed using two-dimensional polyacrylamide gel electrophoresis; then, the isolated proteins associated with cheese production were identified. The research also focused on identifying the optimal method of cheese production based on the coagulation process, temperature, yield, and sensory evaluation. Lupin curds from the two cultivars, Mandelup and PBA Jurien, were produced using vinegar, lemon juice, starter culture, vegetable rennet enzyme as coagulant, as well as curd generated using starter culture and vegetable rennet enzyme. Cow’s milk was used as a control. The results indicated that first-time filtration produced better extraction and higher yield of lupin proteins and cheese than the second filtration. A sensory analysis indicated that lupin cheese produced from PBA Jurien lupin milk using vinegar, 7.80% expressed as acetic acid, and ground in 45 °C water, was the most acceptable. The cheeses were examined for their protein, carbohydrates, fat, ash, and moisture contents. The concentration of protein was approximately 27.3% and 20.6%, respectively, in the cheese from PBA Jurien and Mandelup. These results suggest that lupin milk can adequately supply the proteins needed in human diets and, thus, could be used in the production of many existing products that require animal milk as an input.     

气相双原子分子自交换电子转移过程中重组能与活化能的相关分析

基于电子转移过程中的基本特征，提出了标度电子转移过程活化能和重组能的两种精确确定方案，并利用有关实验光谱数据拟合的精确势函数对气相双原子分子自交换过程的能量指标进行了确定．分析表明势能面的非谐性修正是重要的，该方案是合理的，所得结果吻合较好，并证明了重组能与活化能并不存在简单的４倍关系．     

Aqueous Electrochemistry of Anthraquinone and Its Correlation with the Dissolved States of a Cationic Surfactant

Cyclic voltammetry was employed to study the electrochemical behavior of anthraquinone (AQ) in aqueous solution at a glassy carbon electrode using the sodium salt of anthraquinone-2-sulphonic acid (AQS). The cyclic voltammograms show a reduction wave and a corresponding oxidation wave. The electrochemical reaction of AQ in aqueous solution involves a two electron transfer process followed by a coupled chemical reaction and exhibits strong pH dependence at low pH (<4). A satellite peak is also observed at the cathodic side of the reduction wave for the reduction of the sulfonate group of AQS. The electrochemical investigation was also carried out in the presence of a cationic surfactant, cetyltrimethylammonium bromide (CTAB). Similar redox behavior can be observed for the electrochemical reaction of AQS in the presence of CTAB solutions similar to the aqueous media. The electrochemical responses have been found to depend on the dissolved states of the surfactant. The current-potential behavior of AQS depends on the concentration of CTAB and micellization has a profound effect on the electrochemical behavior of AQ.     

The Natural Occurrence of the Campholenyl Skeleton,Another «Non-isoprenoid» Monoterpene System

In the essential oil of Juniperus communis L. (fruit), campholenic aldehyde and its epoxide have been identified, together with the corresponding alcohol and its acetate. This is the first time the natural occurence of 2-(2,2,3-trimethylcyclopent-3-en-1-yl)-ethyl system is reported.