Schiff碱配合物模拟酶催化性能的温度效应研究

研究了新型Schiff碱双锰配合物在模拟酶催化亚碘酰苯单加氧化环已烷反应及 被亚碘酰苯氧化破坏反应中的温度效应。结果表明，在模拟酶催化反应体系中同时 存在催化环已烷单加氧反应及催化剂的氧化破坏反应；催化反应速率及氧化破坏反 应速率均随反应温度升高有规律地增大，但氧化破坏反应比催化反应对反应温度更 敏感；催化反应总产率一般随反应温度升高而降低；最适宜的反应温度为25 ℃。     

Hydrothermal Synthesis, Crystal Structure, and Characterization of a Novel Terbium（Ⅲ） Coordination Polymer Bridged by 5-Sulfoisophthalate Trivalent Anions

Introduction Recently, several efforts have been made for thestudy of coordination polymers assembled from lantha-nide ions and aromatic polycarboxylate ligands becauseof their intriguing structural diversity and potentialapplications in several fields, s…     

海水养殖鱼类肌肉中微量元素的测定

应用原子吸收光谱法测定了湛江海域十种养殖鱼类肌肉中微量元素的含量。结果表明,海水养殖鱼肌肉中含有丰富的K、Na、Mg、Ca、Zn、Fe等微量元素,经常食用,可以提高机体的免疫力,增强体质,能较好地满足人体对微量元素的需要。     

Canonical Connections and Algebraic Ricci Solitons of Three-dimensional Lorentzian Lie Groups

In this paper, the author computes canonical connections and KobayashiNomizu connections and their curvature on three-dimensional Lorentzian Lie groups with some product structure. He defines algebraic Ricci solitons associated to canonical connections and Kobayashi-Nomizu connections. He classifies algebraic Ricci solitons associated to canonical connections and Kobayashi-Nomizu connections on three-dimensional Lorentzian Lie groups with some product structure.     

Syntheses and structures of magnesium pyridine thiolates--model compounds for magnesium binding in photosystem I

Novel magnesium pyridine-2-thiolates were prepared by using alkane elimination chemistry. The resulting complexes display a metal coordination environment composed of sulfur/nitrogen bonding from the intramolecularly stabilized mercaptopyridine ligand, in addition to coordination by the oxygen centers from two THF donors. The compounds are well-suited model compounds for the magnesium centers in Photosystem I, in which magnesium, situated in the central chlorophyll ligand, is bound to sulfur from a nearby methionine residue. All compounds were characterized by (1)H, (13)C NMR, and IR spectroscopy, in addition to Xray crystallography.     

Determination of Arsenic Species in Fish Oil After Acid Digestion

Arsenic speciation is of increasing interest to the food industry, as concerns about high total arsenic concentrations in food can often be alleviated to a great extent if the ratio of toxic, less toxic and non-toxic arsenic compounds in the sample is known. The lipid matrix of fish oil is a challenge in the determination of arsenic species, as current methods for this type of analysis require the analyte to be water-soluble. In this study, two sample preparation techniques were applied. One the one hand water-soluble species were extracted with methanol/water, on the other, acid digestion was applied to release lipid-soluble arsenic compounds into the aqueous phase. Ion chromatography – inductively coupled plasma mass spectrometry (IC-ICP-MS) was used for separation and sensitive element-specific detection of arsenic compounds. Additional experiments, including alkaline hydrolysis, were carried out to find out more about the type of lipids arsenic is bound to in fish oil. Up to eight different arsenic species were detected and quantified in fish oil with dimethylarsinate being the major compound both in the aqueous extract and in the acid digest. No inorganic arsenic was detected in the aqueous extract, and the maximum concentration of arsenate determined in the acid digest was 0.05 μg g⁻¹. The total arsenic concentration determined by ICP-MS ranged from <0.1 to 5 μg g⁻¹. With regard to the mass balance, approximately 1% of the total arsenic content was extractable with methanol/water, whereas the sum of arsenic species quantified after acid digestion yielded 85–100% of the total arsenic content. It was confirmed that the large fraction of arsenic in fish oil not extractable on an aqueous basis consists of organoarsenic compounds. This new approach in sample preparation makes the complete characterization of the arsenic content in the sample possible with regard to the respective species, providing necessary information required for risk assessment.     

铜(Ⅱ)-邻菲咯啉-(邻菲咯啉-5,6-二酮)络合物的合成及其同脱氧核糖核酸的作用

以邻菲咯啉（phen)、邻菲咯啉－5，6－二酮（dione)为配体首次合成了高氯酸邻菲咯啉－邻菲咯啉－5，6－二酮（Ⅱ）。用荧光光谱，摩尔比，粘度，MLCT减色效应，平衡常数以及荧光能量转移研究了各合物与鱼精子DNA的结合情况，证实了该络合物与DNA存在插入作用。基于络合物对DNA能量转移造成荧光量子产率比值（Φλ/Φ320）的降低，解释了不同波长激发光下，荧光发射峰在加入DNA后产生猝灭和增强两种绝然不同的现象。     

Selective functionalization at the small rim of calix[6]arene. Synthesis of novel non-symmetrical N3, N4 and N3ArO biomimetic ligands

Eight novel calix[6]arene-based biomimetic ligands for transition metal ions have been synthesized. They display a non-symmetrical N₃, N₄ or N₃ArO binding core that mimics enzyme active sites presenting histidine and tyrosine residues. The key step for their synthesis is the mono-alkylation at the small rim of the C_3v symmetrical trimethyl ether derivative of tBu-calix[6]arene with N-Boc-2-chloroethylamine to yield a novel calix[6]arene synthon. Its combined O-alkylation with a chloromethyl aromatic amine and N-deprotection or alkylation or reductive alkylation with a salicylaldehyde derivative yielded the calix[6]arene-based ligands with mixed N/O donors.     

An evaluation of molecular models of the cytochrome P450 Streptomyces griseolus enzymes P450SU1 and P450SU2

Summary P450SU1 and P450SU2 are herbicide-inducible bacterial cytochrome P450 enzymes from Streptomyces griseolus. They have two of the highest sequence identities to camphor hydroxylase (P450cam from Pseudomonas putida), the cytochrome P450 with the first known crystal structure. We have built several models of these two proteins to investigate the variability in the structures that can occur from using different modeling protocols. We looked at variability due to alignment methods, backbone loop conformations and refinement methods. We have constructed two models for each protein using two alignment algorithms, and then an additional model using an identical alignment but different loop conformations for both buried and surface loops. The alignments used to build the models were created using the Needleman-Wunsch method, adapted for multiple sequences, and a manual method that utilized both a dotmatrix search matrix and the Needleman-Wunsch method. After constructing the initial models, several energy minimization methods were used to explore the variability in the final models caused by the choice of minimization techniques. Features of cytochrome P450cam and the cytochrome P450 superfamily, such as the ferredoxin binding site, the heme binding site and the substrate binding site were used to evaluate the validity of the models. Although the final structures were very similar between the models with different alignments, active-site residues were found to be dependent on the conformations of buried loops and early stages of energy minimization. We show which regions of the active site are the most dependent on the particular methods used, and which parts of the structures seem to be independent of the methods.     

活性聚苯乙烯膜诱导碳酸钙异相成核结晶

0引言生物矿物材料(如骨、牙齿、贝壳等)的优异性能[1]使得无机材料的仿生合成(又称有机模板合成)成为近年来研究的热点之一[2]。该合成技术的优点是,通过有机物分子与无机离子的相互作用,能够在温和的条件下合成出具有多级结构、特殊形貌和优异性能的有机/无机复合材料。CaCO3