管华诗，学者凯发k8国际首页主页-凯发网

the strategy of complex as ligand allowed us to synthesize three new l-oxalato-bridged heterotrinuclear complexes identified as [cu2cr(ox)3(mephen)2] clo4 (1), [cu2fe(ox)3(mephen)2] clo4 (2) and [cu2fe(ox)3(me2bpy)2] clo4 (3), where ox represents the oxalato dianions; mephen and me2bpy stand for 5-methyl-1, 10-phenanthroline and 4, 40-dimethyl-2,20-bipyridine, respectively. the three heterotrinuclear complexes have not yet been isolated in crystalline form suitable for x-ray structure analysis, but based on elemental analyses, molar conductivity and magnetic moment (at room temperature) measurements, ir, esr and electronic spectra studies, it is proposed that these complexes have an oxalato-bridged structure consisting of two copper (ii) ions and a chromium (iii) or an iron (iii) ion, in which the chromium (iii) or iron (iii) ion has an octahedral environment, and the two copper (ii) ions have a square-planar environment. variable-temperature magnetic susceptibility (4.2-300k) measurements of the complexes 1 and 2 revealed the occurrence of an intramolecular ferromagnetic interaction between the copper (ii) and chromium (iii) ions for 1. on the other hand, the spin-coupling between the copper (ii) and iron (iii) ions through the oxalato-bridge in complex 2 is an antiferromagnetic. the magnetic data have been also used to deduce the indicated heterotrinuclear structure. on the basis of the spin-hamiltonian, ^h% 2jð^scu1 ^smþ ^scu2 ^smþ (m%cr3þ or fe3þ), the magnetic analysis was carried out for the two complexes and the spin-coupling (j) was evaluated as 14.9cm 1 for 1 and) 12.7cm 1 for 2.

oligomannuronic acids and oligoguluronic acids were prepared by enzymatic hydrolysis of alginate with alginate lyases. the oligosaccharides generated up to degree of polymerization 16 were characterized by high-performance anion-exchange chromatography (hpaec) with pulsed amperometric detection (pad) and electrospray ionization mass spectrometry (esi-ms). acetate buffer linear gradients were used as mobile phases for separations of oligosaccharides. esi-ms and hpaec-pad are very effective for the analysis and characterization of anionic oligosaccharides.

macromolecular alginate extracted from brown seaweeds was treated with acid to generate mannuronate blocks. the resulting polymannuronates were degraded by hydrogen peroxide with a procedure optimized for obtaining high recovery of low molecular weight saccharides. the resulted mixture of different sized oligomannuronates was separated by gel chromatography on a bio-gel p-4 column and mono q column. the purified oligomers were characterized by anion-exchange hplc as well as spectrum analysis. this report provides a general procedure for generation and purification of oligomannuronates with in the size of 2-7 sugar units from alginate.

oligosaccharides were prepared through mild hydrochloric acid hydrolysis of k-carrageenan from kappaphycus striatum carrageenan. three oligosaccharides were purified by strong-anion exchange high-performance chromatography. their structure was elucidated using mass spectral and nmr data. negative-ion electrospray ionization (esi) mass spectra at different fragmentor voltages provided the molecular weight of the compounds and unraveled the fragmentation pattern of the k-carrageenan oligosaccharides. 2d nmr techniques, including 1h-1h cosy, 1h-1h tocsy and 13c-1h hmqc, were performed to determine the structure of a trisulfated pentasaccharide. 1d nmr and esims were used to determine the structures of a carrageenan-derived pentasaccharide, heptasaccharide, and an undecasaccharide. all the oligosaccharides characterized have a 4-o-sulfo-d-galactopyranose residue at both the reducing and nonreducing ends.

alginate that was purified from the fermentation solution of marine bacteria vibro sp.510 under specific reaction conditions was hydrolyzed by alginate lyase. seven oligosaccharides, including di-, tri-and tetrasaccharides, were isolated through low-pressure, gel-permeation chromatography (lp-gpc) and semipreparative strong-anion exchange (sax) fast-protein liquid chromatography (fplc). the oligosaccharide structures were elucidated based on esims and 2d nmr spectral analysis. the hydrolytic specificity of this alginate lyase to alginate is discussed.

sulfated polymannuroguluronate (spmg), a marine sulfated polysaccharide, has entered the phase ii clinical trial in china as the first anti-acquired immune deficiency syndrome (aids) drug candidate obtained from marine organisms. to determine the binding site (s)(receptors) of spmg in lymphocytes mediating its anti-aids activities, fluorescein-5-isothiocyanate (fitc)-labeled spmg was used to investigate spmg binding to lymphocytes. flow cytometry (fcm) and fluorescence microscopy analysis showed that the spmg binds to lymphocytes in a rapid, specific, reversible, and saturable fashion. several spmg binding proteins were purified by affinity chromatography from lymphocyte membrane preparations. sodium dodecyl sulfate polyacrylamide gel electrophoresis (sds-page) and western blotting analysis revealed that a 55 kda lymphocyte membrane protein is cd4. to characterize the spmg and cd4 interaction, inhibition assay and surface plasmon resonance (spr) assay were carried out. spmg bound to cd4 in a multivalent fashion with specificity. the binding of spmg to human lymphocyte cd4 was competitively inhibited by human soluble cd4 (hscd4). likewise, the binding between hscd4 and immobilized spmg was blocked by excess free spmg. these results indicate that cd4 is one of the specific spmg binding sites (receptors) in lymphocytes. the interaction between spmg and cd4 may provide a mechanistic explanation of the immunopotentiating and anti-aids activities of spmg in human immunodeficiency virus (hiv) infected individuals.

海洋是一个巨大的药源宝库。本世纪60年代以来，从海洋动物、植物及微生物中已分离获得新型化合物10000多种，其中1/2以上具有抗肿瘤、抗菌、抗病毒、抗凝血等药理活性；这些新型化合物为药物设计提供了可贵的分子模型，为海洋药物的开发提供了重要的先导化合物库。然而将这些活性化合物开发成药、用于临床的并不多。究其原因，药源是制约其海洋药物产业化的关键因素。纵观海洋药物研究现状、发展趋势, 基于现有的工作基础，我们认为通过半合成手段、结合组合化学原理、利用海洋生物技术进行海洋药物开发是解决药源的关键。

two new complexes [cu(n,n0,n00-(d-glc)3-tren)cl]cl (1) and [cu(n,n0,n00-(maltose)-tren)] cl2æh2o (2), have been synthesized and characterized by elementary analysis, and the ir and uv spectra suggest that complex 1 and complex 2 are arranged in trigonal bipyramidal configuration and square-pyramidal configuration, respectively. the crystal structure of complex 1 has been determined by x-ray diraction as: a% 9: 3476ð8þ, b% 17: 4236ð13þ, c% 9: 7836ð8þ a, b% 91: 197ð3þ, v% 1593: 1ð2þ a3, z% 2, and r% 0: 0325, which shows that three secondary amine groups (n-1, n-2, n-3) of the glycosylamine ligand forms the equatorial plane, and the tertiary amine (n-4) and one cl are located at the apical positions.

ver and seawater solutions diluted with the changjiang river water at one atmoshpere from 5-35 salinity and 15-25℃ with a high precision magnetic float densimete designed by us. the average standared deviation of measurement values was ±2.3×10-3kg/m3. the stawtistical results have shown hat for all samples form the estuary of chingjiang river, the measured density with our densimeter was always higher than the density calculatedby the unesco equation, the average difference, for seawater samples taken in dryseason and flodseason, being (6.3±2.3)×10-3kg/m3 and (8.1±2.3)×10-3kg/m3, respectively. the average difference between the measured and calculated densitied in creasedwith decreasedsalinityand reached 47.2×10-3kg/m3 (chanjiang river water). we have also found linear correlation relationships between this average diffrence and [ca2 ]/s value. our experimental average valueof of [ca2 ]/s, [so2-]/s, [mg2 ]/s and [sr2 ]/s was 0.01183±1.0×10-4, 0.07698±17.×10-4, 0.03743±8.1×10-5 and 2.26×10-4, respectively, at the salinities of samplesrange form 30 to 35. the experimental value of [ca2 ]/s for the wuhu section of changjiang river was 0.2597. the resulting densities of all samples have benn fitted to an equation of the form: d-dw=b1s1/2 b2s b3s3/2 b4s2, where dw is the denstiy of smow and b1, b2, b3, b4, are temperature dependent parameters. the average standard deviation betweem calculated densities of this equation and experimatal value was ±3.9×10-3kg/m3.

the potential targets of marine sulfated polymannuroguluronate (spmg) involved in inhibition of hiv-1 entry were investigated by surface plasmon resonance and flowcytometry. results indicated that binding of spmg either to soluble oligomeric rgp120 or to complexed rgp120-scd4 mainly resided in v3 loop region. in addition, spmgwas shown to be less accessible for scd4 when scd4 had pre-interacted with rgp120, though spmg perse multivalently bound to scd4 with relatively low affinity. while the pre-incubation of spmg with rgp120 caused a partial blockade of rgp120 binding to scd4, suggesting that spmg either shared common binding sites on gp120 with scd4 or masked the docking sites of gp120 for scd4. taken together, v3 domain was demonstrated to be the major site mediating interaction of spmg with complexed rgp120-scd4. it seems likely that spmg binds to both rgp120 and scd4, but has less accessibility for scd4 when scd4 has already bound to rgp120. nevertheless, addition of spmg either prior to or after the interaction of rgp120 with scd4 may suppress rgp120 binding to scd4. the exact pattern of this trimolecular complex formation at the cell membrane-anchored virus level requires further clarification.