鸟嘌呤与氨基酸残基体系的极化力场

发展了应用于鸟嘌呤G和氨基酸残基体系的浮动电荷力场, 该力场明确定义了孤对电子和键的电荷和位置, 通过电荷随着环境的浮动来体现极化效应; 通过氢键拟合函数k_HB描绘了氢键键能. 应用量子化学方法, 对G与氨基酸残基体系从氢键、 几何结构及电荷分布3个方面展开计算及分析, 并以其为基准, 确定参数发展了适用于G与氨基酸残基氢键体系的ABEEMσπ PFF. 采用3种不同力场模拟目标分子的结构和性质. 模拟结果表明, 发展的ABEEMσπ PFF与量子化学方法具有最好的一致性, 可用于模拟生物大分子体系.     

表面带负电荷氨基酸残基的突变对细胞色素bs与细胞色素c结合和识别的影响

利用核磁共振方法研究表面带不同负电荷氨基酸残基突变后的细胞色素b5与细胞色素c的结合与识别，结果表明，静电作用在细胞色素b5与细胞色素c的结合过程中有着重要的贡献，而且这些静电贡献在一定程度上具有 加性，E48的贡献略大于E44。同时还证明Brownian dyanmics simulations优化出的Glu48-Lys13,Clu56-Lys87,Asp60-Lys86和heme 6-propionate-Tml72（细胞色素b5的残基排在前面）的结合方式在溶液中的确存在，细胞色素b5突变体9E48，E56／A，D60／A）及[Cr(oxalate)3]^3－对细胞色素c的表面竞争实验表明，细胞色素c表面结合区SiteⅢ仍然同细胞色素b5突变体9E48，E56／A，D60／A）有结合作用，只是结合强度上相对于野生细胞色素b5同细胞色素c的结合有所降低，这表明除上述的Browni-an dynamics simulations模型外，尚有其它如Salemme模型等的结合方式，这也揭示出细胞色素b5和细胞色素c之间的结合是比较动态的。     

六胜肽片段的液相合成及组装研究

六胜肽是一种药妆肽,序列为Ac-Glu-Glu-Met-Gln-Arg-Arg-NH2,是相对安全的类肉毒素活性物质.拟用液相方法分别合成片段A[Ac-Glu(Ot Bu)-Glu(Ot Bu)-Met-OH]和片段B[H-Gln(Trt)-Arg-Arg-OH],然后将两个片段在固相载体上进行组装,经切割、纯化得到六胜肽产品,纯度大于98%,片段组装的收率为65%,并对组装反应的条件进行分析和讨论.该方法结合了固相和液相合成的优点,是一种成本低廉、收率较高和周期较短的六胜肽合成方法.     

水溶液中磷酰化组氨酸与其它氨基酸的交叉成肽研究

水溶液中磷酰化组氨酸与其它氨基酸的交叉成肽研究沙耀武，赵玉芬（清华大学化学系，北京１０００８４）一些氨基酸在前生化时期的条件下，就可以由甲烷、氨和水通过高压放电生成［１，２］。如果向该反应体系中加入三氢化磷，生成的氨基酸的种类增多、结构的复杂性也提高...     

多肽片段连接方法及肽硫酯和肽醛的合成*

本文综述了多肽和蛋白质合成中的片段连接方法,这是近年来多肽和蛋白质合成领域中方法学上的重要进展.该方法使用非保护的多肽片段,无需酶或化学活化试剂,在缓冲溶液中能够高产率地获得多肽和蛋白质.还介绍了与多肽片段连接有关的肽硫酯和肽醛的合成方法.     

依据氨基酸残基的相关性预测蛋白质的结构类型

作为蛋白质的建筑构件,各种类型的蛋白质的20种氨基酸残基之间存在着特定的相互关联,反映了氨基酸残基之间的制约性,并有深刻的物理和化学的内在因素.某些氨基酸残基对之间的相关系数可以作为一种类型的蛋白质区别于其它类型蛋白质的特征,用于蛋白质结构类型的预测.研究了4种类型的蛋白质204个样品的氨基酸残基对的相关性系数,找出了可作为蛋白质结构类型特征的氨基酸残基的相关对,并用于蛋白质结构类型的预测,对于α型、β型、α/β型和α＋β型蛋白质的204个蛋白质样品的交叉测试,正确率分别为94％、89％、79％和89％,平均为88％,高于简单距离法和欧几里德距离法.     

兔早期胚泡特异肽的cDNA克隆

从家兔受精后第6天(着床前)的早期胚泡构建cDNA文库,经阶段特异分子杂交筛选,克隆了仅在此时期表达的9种胚泡特异肽类的cDNA对其中一种丰度较高的cDNA克隆进行了研究,测出其编码区含有285碱基对,5'和3'侧翼区各有132和170碱基对.经DNA序列分析,推导出一种分泌性多肽的一级结构,由75个氨基酸组成.计算机分析显示它与迄今报道的所有基因和蛋白在结构上无任何同源性.     

氨基酸和肽的电致化学发光流动注射分析

利用联吡啶钌化合物（Ⅱ）Ｒｕ（ｂｐｙ）＾２＋３对一些氨基酸，肽和含氮化合物的电致化学发光流动注射分析进行了研究。在弱碱性水溶液中Ｒｕ（ｂｐｙ）＾２＋３在玻碳电极表面于＋１．３５Ｖ（ｖｓ．Ａｇ／ＡｇＣｌ）处经为Ｒｕ（ｂｐｙ）＾３＋３，并有发光现象出现，微量的氨基酸，肽和茜些含氮化合物加入会对发光有明显的增强作用。实验结果表明在１９种氨基酸中，该方法的检出限从羟基脯氨酸，脯氨酸的０．１ｐｍｏｌ升至丝氨     

N-磷酰化肽酯及小肽与氨基酸相互作用的ESI-MS研究

采用ESI-MS研究了一系列结构具有可比性的N-二异丙氧基磷酰化肽酯及小肽同20种蛋白氨基酸及3种D型氨基酸(D-Ala、D-Ser、D-Phe)的非共价相互作用.结果表明,可形成π-π共轭体系的芳香环,可显著增强磷酰化肽酯及小肽与氨基酸的相互作用力,π-π堆积力是首要的非共价相互作用力;可形成氢键的极性基团有利于形成复合物,但能否形成氢键还要受到分子柔顺性的影响;另外,分子大小、空间位阻对复合物的形成也有影响;而氨基酸的手性对它们的相互作用在质谱条件下没有表现出影响.     

罂粟花粉十七肽类似物和片段的合成及其抗肿瘤活性研究

以从罂粟花粉中分离得到的具有促免疫和抗肿瘤活性的十七肽为先导化合物,设计了4个类似物和3个片段,并用固相法合成,通过CD谱测定了它们在溶液中的初级二级结构,同时测定了它们对人胃癌和人膀胱癌肿瘤细胞的抑制活性,初步讨论了构效关系.     

基于核酸适体与互补核酸和目标蛋白之间竞争反应的PDGF蛋白特异性识别

报道了一种利用核酸适体与互补核酸和目标蛋白之间的竞争反应用于PDGF蛋白的特异性识别方法.采用反相微乳液技术制备了包覆有亚甲基蓝(MB)的SiO2纳米复合物(SiO2-MB),利用固定在磁性纳米颗粒上的核酸适体与SiO2-MB纳米颗粒标记的互补核酸进行杂交反应,将一定数量的SiO2-MB纳米颗粒固定于磁性纳米颗粒的表面...     

Specific Proteins in the Indirect Somatic Embryogenesis of Freesia

Using the young inflorescence segments of Freesia refracta as explants, indirect somatic embryogenesis of somatic cells was induced in a N6 medium supplemented with some exogenous hormones. SDS-polyacrylamide gel electrophoresis（SDS-PAGE） was used for the analysis of soluble proteins produced during the somatic embryogenesis of this plant. There are six polypeptides, which might play some roles in the process of somatic embryo development. Tltree polypeptides（45, 53 and 55 kD） were detected in the stages of embryogenic callus, globular embryoid, and embryoid with coleoptiles, except the embryoid with leaf. One polypeptide（ 83 kD） was specific for the stages of embryoid with eoleoptiles and embryoid with leaf. One polypeptide（37 kD） was detected in the first two stages, namely, embryogenic callus and globular embryoid. One polypeptide（35 kD） was regularly synthesized in each stage, from embryogenic callus to embryoid with leaf.     

Specific Proteins in the Indirect Somatic Embryogenesis of Freesia Refracta

IntroductionHaberlandt[1]proposed the conception of plantso-matic embryo in 1902, which states that plant cellsexhibit totipotency; each cell could divide ceaselesslyand eventually develops into a mature plantlet. Allthese provide a theoretical evidence for somatic embryo-genesis. The related researches reveal thatplantembry-ogenesis occurs as a result of the selective expression ofsets of genes that allowthe synthesis of special proteinsin a temporal and spatial sequential manner under themut…     

适配体在靶向特异性检测中的最新应用进展

适配体是体外采用SELEX技术筛选得到的一段寡核苷酸序列(DNA或RNA),能折叠成一定的空间结构结合靶物质,实现特异性吸附。其功能类似抗体,但具有抗体无法比拟的优势,如靶物质范围广、特异性强、亲和力高、可体外筛选、易于标记和修饰、稳定性好、没有毒性、易制备等。近年来,适配体已在分析检测、生物化学、食品安全、临床医疗等领域得到广泛应用。本文综述了适配体在金属离子、抗生素、农药残留、真菌毒素、蛋白质、微生物、细胞等成分靶向特异性快速检测方面的应用进展,并分析其存在的局限性和问题,展望其应用前景和发展趋势,以期为适配体应用的拓展和相关研究提供依据和支持。     

Specific Electrostatic Molecular Recognition in Water

The identification of pairs of small peptides that recognize each other in water exclusively through electrostatic interactions is reported. The target peptide and a structure‐biased combinatorial ligand library consisting of ≈78 125 compounds were synthesized on different sized beads. Peptide–peptide interactions could conveniently be observed by clustering of the small, fluorescently labeled target beads on the surface of larger ligand‐containing beads. Sequences of isolated hits were determined by MS/MS. The interactions of the complex showing the highest affinity were investigated by a novel single‐bead binding assay and by 2D NMR spectroscopy. Molecular dynamics (MD) studies revealed a putative mode of interaction for this unusual electrostatic binding event. High binding specificity occurred through a combination of topological matching and electrostatic and hydrogen‐bond complementarities. From MD simulations binding also seemed to involve three tightly bound water molecules in the interface between the binding partners. Binding constants in the submicromolar range, useful for biomolecular adhesion and in nanostructure design, were measured.     

核酸适体-纳米材料复合物用于癌症的诊断与靶向治疗研究进展

因具有独特的光、电、磁、热等优异性能,纳米材料已被广泛应用于生物分析与生物医学领域。核酸适体是一类能够高亲和力和高特异性地与靶标结合的寡核苷酸序列。将核酸适体作为识别单元与纳米材料相结合,可以构建核酸适体-纳米材料复合物。近年来,在肿瘤靶向治疗方面,核酸适体-纳米材料复合物受到了人们的广泛关注。通过纳米材料与具有特异性识别能力的核酸适体的结合,核酸适体-纳米材料复合物可以为癌症治疗提供一种更有效的、低毒副作用的新策略。本文综述了核酸适体-纳米材料复合物作为药物输送载体在癌症的特异性识别与诊断及靶向治疗方面的应用。除此之外,本文还总结了核酸适体-纳米材料复合物与其他新兴技术的有效结合从而提高选择性和癌症治疗效率的相关研究进展。     

Specific Transport of Target Molecules by Motor Proteins in Microfluidic Channels

Direct transport powered by motor proteins can alleviate the challenges presented by miniaturization of microfluidic systems. There have been several recent attempts to build motor‐protein‐driven transport systems based on simple capturing or transport mechanisms. However, to achieve a multifunctional device for practical applications, a more complex sorting/transport system should be realized. Herein, the proof of concept of a sorting device employing selective capture of distinct target molecules and transport of the sorted molecules to different predefined directions is presented. By combining the bottom‐up functionality of biological systems with the top‐down handling capabilities of micro‐electromechanical systems technology, highly selective molecular recognition and motor‐protein‐based transport is integrated in a microfluidic channel network.     

固载化酶催化合成多肽的研究进展

评述了溶剂、载体性质与固载化方法、pH值、底物浓度以及反应温度等因素对固载化酶催化合成肽反应的影响,并概括了固载化酶催化合成生物活性肽、寡肽等方面的研究与应用.     

A Hairpin Electrochemical Aptasensor for Sensitive and Specific Detection of Thrombin Based on Homogenous Target Recognition

An electrochemical aptasensor was developed for sensitive and specific detection of thrombin by combining homogenous recognition strategy and gold nanoparticles (AuNPs) amplification. Streptavidin‐alkaline phosphatase was used as reporter molecule. Compared with the traditional hairpin aptasensor monitoring the distance of the redox molecule from the electrode surface, the proposed aptasensor successfully overcome the limitations of distance and improved the stability and high affinity of the aptamer hairpin through homogenous recognition, which enhanced the sensitivity and selectivity of the sensors effectively. Additionally, AuNPs were employed to increase the active area and conductivity of the electrode, thus, improving the sensitivity of the aptasensor. As a result, the designed thrombin detection sensor obtained a lower detection limit of 0.52 pM in buffer and 6.9 pM in blood serum.