Synthesis, electrochemistry and metal binding properties of monosubstituted ferrocenoyl peptides with thioether-containing sidechains

Ferrocenoyl peptides incorporating thioether functionality respond more strongly to mercury(II) than to other heavy metal ions in solution. Compounds reported previously in this context are all 1,1′-disubstituted, and all include two or more sulfur-containing amino acids. To test whether two thioether groups are required for effective mercury binding by these systems, we have prepared a series of singly-substituted ferrocenoyl peptides from ferrocenecarboxylic acid and l-methionine, S-methyl-l-cysteine or S-trityl-l-cysteine, and tested them as electrochemical probes for mercury(II). Nine ferrocenoyl peptides have been synthesised using a Boc-protecting group strategy and HBTU-mediated peptide coupling. The electrochemical properties of these compounds have been determined using cyclic voltammetry, and all show fully reversible one electron oxidation steps. Forward sweep half wave peaks (E_F), reverse sweep half wave peaks (E_R), peak separations (ΔE_P) and half wave potentials (E_1/2) are reported. Changes in the potential of the iron(II)/iron(III) redox couple of the ferrocene core have been used to quantify heavy metal-peptide interactions, revealing that these monotopic systems also respond more strongly to mercury(II) than to zinc(II), cadmium(II), silver(I) and lead(II). NMR experiments to characterise the peptide-mercury interaction implicate the thioether sulfur as the site of mercury binding and indicate 1:1 stoichiometry. The crystal structure of ferrocenoyl-S-methyl-l-cysteine methyl ester is also reported. The greater responsiveness of these systems to mercury(II) makes them interesting leads for the development of biologically inspired sensors for this toxic heavy metal.     

ADENYLATE CYCLASE-MODULATING MEDIATORS OF INSULIN

Plasma membranes prepared from pig liver incubated with insulin (50—300 μU/ml) resulted in the release of at least two insulin chemical mediators. They appeared to modulate the activity of adenylate cyclase in liver plasma membrances of pig. One of them was fraction 1 of insulin mediator (M. W. about 3700—4000 dalton) which markedly stimulated the activity of the enzyme, the other was fraction 2 of insulin mediator (M. W. about 1000 dalton) which inhibited the enzyme activity. The results showed that the inhibitor of fraction 2 generated was significantly higher than that of fraction 1 when the membranes were incubated with insulin of low concentration (50—100 μU/ml). On the other hand, the generation of stimulator of fraction 1 from plasma membranes incubated with insulin of high concentration (200 μU/ml) was higher than that of fraction 2. So the ratio of yield between two mediators produced from the membranes was dependent on the concentration of insulin added. The results also showed that the     

Determination of creatine and phosphocreatine in muscle biopsy samples by capillary electrophoresis with contactless conductivity detection

A capillary electrophoresis method with contactless conductivity detection was evaluated as a new approach for quantification of creatine and phosphocreatine in human quadriceps femoris biopsy samples. The running buffers employed consisted of 1 M acetic acid at a pH of 2.3 for the determination of creatine and 50 mM 3-(N-morpholino)propanesulfonic acid/30 mM histidine at a pH of 6.4 for the determination of phosphocreatine in the centrifuged muscle extracts. The limits of detection for creatine and phosphocreatine were found to be 2.5 and 1.0 μM, respectively. Creatine and phosphocreatine were determined in six human muscle biopsy samples and the results were found comparable to those of a standard enzymatic assay. The procedures developed for creatine and phosphocreatine also allow the determination of creatinine as well as adenosine diphosphate and adenosine triphosphate.     

Nano-crystalline FeOOH mixed with SWNT matrix as a superior anode material for lithium batteries

Nano-crystalline FeOOH particles(5～10 nm) have been uniformly mixed with electric matrix of single-walled carbon nanotubes(SWNTs)for forming FeOOH/SWNT composite via a facile ultrasonication method. Directly using the FeOOH/SWNT composite(containing 15 wt%SWNTs) as anode material for lithium battery enhances kinetics of the Li+insertion/extraction processes, thereby effectively improving reversible capacity and cycle performance, which delivers a high reversible capacity of 758 mAh g-1under a current density of 400 mA g-1even after 180 cycles, being comparable with previous reports in terms of electrochemical performance for FeOOH anode. The good electrochemical performance should be ascribed to the small particle size and nano-crystalline of FeOOH, as well as the good electronic conductivity of SWNT matrix.     

删截Turbo码中交织器和删截方案的综合设计

删截是构造高码率Turbo码的主要方法，删截方案对于删截Turbo码的性能有重要影响。介绍了删截Turbo码的原理，提出了交织器和删截方案相结合的综合设计思想，设计了一种新的交织器以及相应的删截方案，并给出了该交织器的实现算法，仿真结果表明，该综合设计具有优异的性能。     

高光谱遥感技术在水稻转入基因表达的检测指示作用研究

传统方法在转基因作物目的基因表达检测上做了很多工作,但仍有发展空间。该研究利用野外高光谱仪(ASD野外光谱仪),避免了实验室测量带来温度水分差异造成的影响,实地测量大田水稻样本光谱数据;通过引入内部聚类系数控制类内波段聚合度,使用均值光谱表征样本类光谱,计算与光合作用高度相关的边峰以及光化学植被指数等参数,快速定量了转基因组样本与亲本在光合作用波段的光谱表达差异。研究结果表明转入基因得到了表达、对样本产生了影响,同时发现面积参数适合描述样本差异,而光化学植被指数对样本差异尤为敏感。这些都证明高光谱遥感技术在水稻转入基因表达检测上具有良好指示作用和应用优势,前景看好。     

用影射法求解KdV方程

应用影射法求解KdV方程,得到了KdV方程的物理上有意义的两种类型的行波解,即孤立波解和Jacobi椭圆函数解,并绘图加以说明.     

Analysis on sustainable growth range of population

Based on the summarization and the analysis of the obtained research results, the models for local stability and for global stability of ecosystems are developed by means of the theory of dissipative structures, with which the questions on sustainable growth range of population are answered.     

杜仲胶玻璃化转变温度的分子模拟

对杜仲胶的玻璃化转变温度进行了分子动力学模拟。首先,计算了不同聚合度的反式聚异戊二烯的溶度参数,确定了合理的反式聚异戊二烯结构模型的聚合度为20;然后,用分子动力学模拟获得反式聚异戊二烯在不同温度下的比体积,通过对模拟得到的比体积-温度(V-T)作图,求得玻璃化转变温度(Tg)为210 K,采用差示扫描量热(DSC)法实测得到的Tg为203 K,两种结果在误差允许范围内基本一致,其模拟结果与实测值吻合得较好。     

Magnetic Screening of the Potential Targeted Protein of Salvianolic Acid B Using T7 Phage Display Library

Salvianolic acid B is one of the effective components from the Chinese traditional drug Salvia miltiorrhiza (Danshen), which is widely used as a usual clinic drug for atherosclerosis-related disorder patients in China. But the targeting protein of salvianolic acid B is still not known. The possible targeting proteins of salvianolic acid B were explored by high throughput screening in this paper. Attached to the magnetic nanoparticles, salvianolic acid B was used for screening the high-affinity protein from the displaying cDNA peptide library phage. After biopanning, the selected protein or peptide sequences were used to explore the whole proteins containing the selected sequences in the National Center for Biotechnology Information website using blast. One of the selected phages was carried out by affinity analysis with salvianolic acid B using capillary electrophoresis (CE). The CE results indicated that the protein or peptide on the surface of the selected phages could bind the drug salvianolic acid B. The results are helpful to preliminarily explain the pharmacology of salvianolic acid B.