Preparation of Chitosan-coated Nylon Membranes and their Application as Affinity Membranes

Chitosan-coated nylon membranes which possess a large number of reactive groups of-CH2OH and -NH2 were prepared by coupling chitosan onto the nylon membrane. Then polylysine as ligand was also immobilized onto the composite membranes by 1, 1＇-carbonyl-diimidazole activation to prepare affinity membranes for bilirubin adsorption. The results showed that these membranes exhibited high binding affinity capacities for bilirubin and the adsorption isotherm fitted the Freundlich model well.     

Interactions of ginsenosides with DNA duplexes： A study by electrospray ionization mass spectrometry and UV absorption spectroscopy

The non-covalent complexes of duplexes DNA and 9 ginsenosides（1 aglycone and 8 glycosides） were investigated using electrospray ionization mass spectrometry（ESI-MS） in the gas phase. The results of relative binding affinities in negative ion mode revealed that several factors impact on the duplexbinding properties of ginsenosides. Glycosylations of 20（S）-protopanaxadiol ginsenosides at the position C-20 and 20（S）-protopanaxatriol classification at the position C-6 enhanced the fraction of bound DNA sharply. A rhamnose moiety shows little lower binding intensities than glucose at the same position.Ginsenosides of 20（S）-protopanaxatriol result in subtle higher binding affinities toward the duplex DNA than 20（S）-protopanaxadiol family. However, glycosylation with two sugar moieties does not show a higher binding affinity than with only one moiety. The collision-induced dissociation experimental data demonstrate the gas-phase stability and fragmentation patterns of the ginsenoside/DNA complexes are related to the glycoside number. Positive ion ESI mass spectra of the complexes were also recorded. The result of ESI-MS suggests that hydrogen bonds are the dominate interaction between ginsenosides and DNA. Similar results were obtained in solution-phase by UV spectroscopy, which exhibit a hyperchromism and blue-shift effect when DNA solution was titrated by individual ginsenoside.     

化学修饰提高核酸适体结合亲和力的研究进展

核酸适体(Aptamer)是通过体外筛选得到的短单链DNA或RNA寡核苷酸, 具有与抗体相当或更优异的特异性及亲和力, 且具有靶标范围广、 易制备和灵活可控修饰、 免疫原性低、 批次差异性小以及易于运输保存等优势, 为食品、 环境和生物医学等领域提供了全新的分子识别工具, 获得了研究者的广泛关注. 但是目前其商业应用的数量仍有限. 为了增强核酸适体的应用性能, 研究者对核酸适体进行了大量的改性研究. 本文系统总结了核酸适体筛选前、 后采用非共价或共价方式对其进行化学修饰, 以增加核酸适体与靶标的结合亲和力的相关研究进展, 并对未来发展前景进行了展望.     

基于定点突变的抗克百威单链抗体的亲和力成熟

为获得亲和力更高的抗克百威(CBF)单链抗体(scFv), 从抗CBF scFv氨基酸序列出发, 通过同源模建获得抗体模型, 找出抗体中的活性口袋区域, 进而将小分子药物与抗体进行分子对接, 发现疏水作用和氢键对于抗体亲和力具有重要作用. 进一步对口袋内亲水氨基酸残基HArg40和LHis38进行模拟替换, 再进行分子对接分析, 发现当以亮氨酸为突变氨基酸时, 对接评分最高. 在此基础上, 通过构建突变scFv基因及可溶性表达, 采用ELISA法对进化后的单链抗体(evoscFv)进行了鉴定. 结果表明, evoscFv对CBF的IC₅₀值为18.11 μg/L, 低于野生型抗体的27.25 μg/L, 亲和解离常数K_d为4.06×10^-8 mol/L, 相对亲和力比野生型scFv提高了2.23倍, 说明通过分子对接分析及对抗体活性口袋中氨基酸残基进行替换, 获得了一个亲和力更高的突变体抗体.     

6-取代苯并噻唑苯胺类化合物的合成

以2-氨基苯并噻唑类化合物为原料, 通过碱性条件下水解, 与苯甲酸类化合物在PPA(聚磷酸)条件下脱水环化, 部分化合物通过BBr₃去甲基化反应, 合成了一系列潜在的针对β-淀粉样蛋白的正电子放射性探针分子前体或作为参比的6-取代苯并噻唑苯胺类化合物, 并用¹H NMR, IR, EI/ESI-MS, HRMS, 元素分析等对其进行了表征. 同时测定比较了6种化合物与早老性痴呆(Alzheimer’s disease, AD)死者脑匀浆的亲和力强弱.     

CHEMICAL DERIVATION OF HUMAN INSULIN SUPERAGONISM

The role of three highly conserved insulin residues Tyr^B26 was studied to better understand the relationship between insulin and receptor from rat adipose tissue plasma membranes, lnsulin analogues with a single amino acid substitution or single N-methylation of the peptide bond in the position B26 were all shortened in the C-terminus of the B-chain by four amino acids. The effect of modifications was followed by the binding to the insulin receptor. From our results, we can deduce several conclusions： （1） the replacement of tyrosine in the position B26 by histidine, [N-MeHis^B26]-des-tetrapeptide-（B27-B30）-insulin-B26-amide and [N-MeGlu^B26]-des-tetrapeptide- （B2-B30）-insulin-B26-amide, have no significant effect on the binding affinity and they show binding affinity 105%, 190% and 208%, respectively, of that of human insulin; （2） [Aad^B26] -des-tetrapeptide-（B27-B30）-insulin-B26-amide and [Phe（4-carboxy^B26）]-des-tetrapeptide- （B27~B30）-insulin-B26-amide affect the potency highly positively in vitro studies; they show binding affinity 529 and 289 %, respectively, of that of human insulin.     

实践新课标中的困惑与思考

人教社A版教材依照新课标的10条基本理念,在继承了大纲教材的若干优点的基础上巧妙构思、锐意创新,体现亲和力、问题性、科学性、思想性、时代性与应用性,让人耳目一新．我省2009年秋季正式进入高中新课程,对中学数学教师是一个难得的机遇与挑战．我们通过认真解读新课标、实践新教材,取得了一定的效果,观念不断转变,手段不断更新,境界逐步提高．另一方面,对课程标准、新教材的叫苦声、抱怨声也不少．     

酪氨酸激酶受体多肽片段在SPR传感芯片表面的磷酸化及其与下游蛋白的相互作用

胰岛素样生长因子-1受体(IGF-1R)信号转导通路与各种正常生理活动及多种疾病发生密切相关.将IGF-1R来源的未磷酸化多肽序列LYASVNPEY固定于表面等离子体共振(SPR)生物传感器专用的CM5芯片表面,以含有相应蛋白激酶的细胞裂解液进行处理,利用SPR生物传感器和抗酪氨酸磷酸化抗体PY20进行酪氨酸磷酸化水平检测.结果表明:PY20能灵敏地检测多肽酪氨酸磷酸化水平变化,即能够区分不同孵育时间以及不同成分的细胞裂解液所引起的多肽酪氨酸磷酸化水平差异;研究了IGF-1R来源多肽的酪氨酸磷酸化对多肽-蛋白间相互作用的影响,证实了只存在磷酸化的多肽与其下游的胰岛素受体底物(IRS-1)相互作用,测定了此磷酸化的多肽与IRS-1的亲和常数(KA)为 (2.02 ± 0.09)×108 L mol-1、结合速率常数(ka)为(2.30±0.15)×106 L mol-1s-1以及解离速率常数(kd)为(1.14±0.13)×10-2 s-1.这种新型的模拟受体的多肽酪氨酸磷酸化研究方法可用于受体磷酸化信号通路的研究以及基于这些信号通路的药物筛选研究.     

Single-Electron Detachment for Ti-, Fe-, Co-, Ni-, and Cu-, in Collision with Ar

By using the micro-channel plate position sensitive detector with the delay-line anode we measure the single electron detachment cross sections for some transition elements in collision with Ar in the energy region 10-30 keV. These single electron detachment cross sections perform as velocity and electron affinity dependences. The experiments are carried out using the growth rate method.     

膳食黄酮类化合物与牛血清蛋白的分子结构亲和力关系

用荧光滴定法研究了食用黄酮类化合物的分子结构及其与牛血清蛋白间的亲和力关系。研究证明食用黄酮类化合物与牛血清蛋白的结合过程在很大程度上受黄酮结构的影响,类黄酮中羟基的甲基化使其与牛血清蛋白的亲和力增长1～794倍。环A、B、C的羟基化作用对类黄酮与牛血清蛋白的亲和力也有很大影响,糖基化作用因共轭位置和糖种类的不同而使类黄酮与牛血清蛋白的结合力降低1～2个数量级。C2‖C3双键的加氢化作用使结合能力稍有减弱。与非聚合型儿茶酚和邻苯二酚型儿茶酚相比,聚合儿茶酚和邻苯三酚型儿茶酚与牛血清蛋白的亲和力更强。分配系数升高时,类黄酮与牛血清蛋白的亲和力增强;氢键的电子供体和受体数目增多时,类黄酮与牛血清蛋白的亲和力降低,表明疏水力是影响其相互结合作用的主要因素。