双N—乙酸取代氮氧杂大环及其镧系配合物的合成

首次合成了一种新的1.2-双(3,4:9,10-二苯并-5,8-二氧杂-1,12-二氮杂环十五烷-N-乙酸)乙烷大环配体,制备了它的8个镧系元素(La,Pr,Nd,Sm,EU,Gd,Dy,Yb)配合物,用红外光谱、元素分析、核磁共振谱及电导等方法进行了表征,讨论了可能的配位情况。     

Synthesis of Obyanamide, a Marine Cytotoxic Cyclic Depsipeptide

Obyanamide 1 is a cyclic depsipeptide that was recently isolated from the marine cyanobacterium Lyngbya confervoides by Moore and co-workers1. This compound displayed a potent inhibitory effect on both KB and LoVo cells in vitro. Several structural analog…     

低温原子化石墨炉原子吸收法测定环境和生物样中的镉

本文描述了以氩/氢混合气体作保护气体,测定环境和生物样品中痕量镉的石墨炉原子吸收法。实验证明,与纯氩气作保护气体相比较用氩/氢混合气体作保护气体,能够降低镉的原子化温度(100℃),并且减少基体物质如MgCl_2和NaClO_4的干扰。这种改善氯化物和高氯酸盐基体干扰的机理,主要是由于氢的存在与基体中的氯形成高离解能的氯化氢,从而避免了通常在镉原子化之前形成易挥发的氯化镉而损失。用本方法测定了七种标准参考物质,结果与标准值一致,证明方法是可靠的。     

烷基吡啶盐和芳基季铵盐作检测和改性剂的羟基酸间接光度高效液相色谱研究

研究了苄基三甲基溴化铵动态改性、十四烷基吡啶盐等“永久性”涂渍的两种反相色谱,系统分离和间接光度检测了强极性、弱紫外吸收羟基酸。测定这些检测和改性试剂在YWG-CH反相填料和甲醇-磷酸缓冲液色谱体系的吸附等温线,探讨试剂在固定相的吸附量和其它因素对羟基酸保留、检测灵敏度的影响及分离检测机理。     

双甘肽稀土配合物溶液结构的13C和1H NMR研究

~(13)C and ~1H NMR technique was used to study the interaction of Gly-Gly with heavy lanthanide cations Dy~(3+), Ho~(3+), Er~(3+), Tm~(3+) and Yb~(3+) in aqueous solution. The stability constants for the 1:1 and 1:2 complexes of Gly-Gly with Ho~(3+) and Yb~(3+) were determined from the titration curves of chemical shift versus concentration ratio of lanthanide to Gly-Gly. The solution structure of the Ln-Gly-Gly complex was analyzed based upon the ~(13)C and ~1H lanthanide-induced shifts and the results show that in the complex Gly-Gly is coordinated to the lanthanide ion through the carboxyl oxygens with the backbone of the ligand in an extended state.     

氨基酸及杂环胺酰乙基锗倍半氧化物合成及对癌细胞的作用

β-羧乙基锗倍半氧化物(即Gc-132)是具广谱药理活性的水溶性有机锗化合物,但因其在体内代谢速度太快而影响药物利用度。因此,对它的各种衍生物的合成和生物活性研究受到重视。为提高Ge-132的亲脂性,增强药物活性,我们在分子中引入具有生物活性的氨基酸或杂环胺,合成了8种新型酰胺衍生物。合成路线如下:     

冰晶石-氧化铝熔体结构的计算机模拟研究

用Monte Carlo法对冰晶石-氧化铝系熔体结构作了计算机模拟研究。结果表明: 熔体中既有含“氧桥”和“氟桥”的“多核”离子集团, 如F3Al-O-AlF_3、F_3Al-AlF_3、F_3Al—F—AlF_3—F等; 也有“单核”离子集团如AlF_5~(2-)、AlOF_3~(2-)等。熔体中还存在较松散的xNa~+·yF~-离子集团。熔体中不存在AlO_2~-或AlO_3~(3-)集团。     

Photodissociation dynamics of pyridine

Photodissociation of pyridine, 2,6-d2-pyridine, and d5-pyridine at 193 and 248 nm was investigated separately using multimass ion imaging techniques. Six dissociation channels were observed at 193 nm, including C5NH5 --> C5NH4 + H (10%) and five ring opening dissociation channels, C5NH5 --> C4H4 + HCN, C5NH5 --> C3H3 + C2NH2, C5NH5 --> C2H4 +C3NH, C5NH5 --> C4NH2 + CH3 (14%), and C5NH5 --> C2H2 + C3NH3. Extensive H and D atom exchanges of 2,6-d2-pyridine prior to dissociation were observed. Photofragment translational energy distributions and dissociation rates indicate that dissociation occurs in the ground electronic state after internal conversion. The dissociation rate of pyridine excited by 248-nm photons was too slow to be measured, and the upper limit of the dissociation rate was estimated to be 2x10(3) s(-1). Comparisons with potential energies obtained from ab initio calculations and dissociation rates obtained from the Rice-Ramsperger-Kassel-Marcus theory have been made.     

Binding of high-mannose-type oligosaccharides and synthetic oligomannose clusters to human antibody 2G12: implications for HIV-1 vaccine design

Human antibody 2G12 broadly neutralizes human immunodeficiency virus type 1 (HIV-1) isolates and shows protective activity against viral challenge in animal models. Previous mutational analysis suggested that 2G12 recognized a novel cluster of high-mannose type oligosaccharides on HIV-1 gp120. To explore the carbohydrate antigen for HIV-1 vaccine design, we have studied the binding of 2G12 to an array of HIV-1 high-mannose type oligosaccharides by competitive ELISAs and found that Man9GlcNAc is 210- and 74-fold more effective than Man5GlcNAc and Man6GlcNAc in binding to 2G12. The results establish that the larger high-mannose oligosaccharide on HIV-1 is the favorable subunit for 2G12 recognition. To mimic the putative epitope of 2G12, we have created scaffold-based multivalent Man9 clusters and found that the galactose-scaffolded bi-, tri-, and tetra-valent Man9 clusters are 7-, 22-, and 73-fold more effective in binding to 2G12 than the monomeric Man9GlcNAc2Asn. The experimental data shed light on further structural optimization of epitope mimics for developing a carbohydrate-based HIV-1 vaccine.