硫酸酯化猴头菌多糖的结构与构象分析

利用碱提醇沉法从猴头菌(Hericium erinaceus)子实体中获得水不溶性多糖HEPFA,氯磺酸-吡啶法对HEPFA进行硫酸化修饰,制得能溶于水的硫酸化猴头菌多糖(S-HEPFA);通过DEAE-Sepharose Fast Flow离子交换柱层析和Sephacryl S-500凝胶柱层析对S-HEPFA进行纯化;运用化学方法和波谱技术对S-HEPFA进行结构分析。碱提醇沉得到相对分子量为5.38×105u,硫酸基含量为19.5%的硫酸酯化的猴头菌多糖(S-HEPFA);红外光谱分析表明,在波数1236cm-1、820cm-1处有硫酸酯键的特征吸收峰;离子色谱检测,该组分只含有葡萄糖,甲基化分析得S-HEPFA糖链主要的葡萄糖残基由1-连接Glcp、1,3-连接Glcp和1,3,6-连接Glcp组成,摩尔比为2.07:1:1.83;刚果红实验分析得S-HEPFA在水溶液中或微碱溶液中为三股螺旋构象。

非变性离子淌度质谱在蛋白质结构及构象疾病研究方面的应用

离子淌度质谱技术可以分离空间尺寸或构象不同的离子,能够在近似生理条件下表征蛋白质及其复合物的构象,可提供蛋白质及其复合物的构象稳定性及异质性、化学计量比等多重信息,已成为蛋白质构象及蛋白质-配体相互作用研究的重要手段。非变性离子淌度质谱还具有灵敏捕获蛋白质构象动态转变的特点,适用于低浓度、高异质性的蛋白混合物分析。本文综述了离子淌度质谱的基本原理、获取数据及信息形式、以及在蛋白质构象及蛋白质-配体相互作用研究领域的应用进展,重点关注其在蛋白质错误折叠、聚集动力学及与配体相互作用的应用研究。

亲水性两性离子聚合物刷的构象与结构

本文应用分子场理论,研究暴露于水蒸气中的亲水性两性离子聚合物(HP)刷的构象与结构.理论模型考虑HP-水(P-W)氢键和水-水(W-W)氢键效应,以及HP单体之间的偶极-偶极相互作用.研究发现,P-W与W-W氢键决定着HP的水合性,P-W氢键形成,会诱导HP刷溶胀.我们通过考察HP单体间的偶极-偶极相互作用发现,随着偶极-偶极相互作用增强,HP链在垂直培基表面沿着链方向,形成了结节状结构.这是由于HP单体之间的偶极-偶极静电吸引作用导致单体间汇聚结节,这种结节在刷内产生了较强的排斥体积作用,因此,这种HP刷具有抗污性能.在较高的接枝密度环境下,由于HP链间单体之间的偶极-偶极静电吸引作用,会形成链间单体-单体的结节,在刷内形成结节网络状凝胶结构,这种结构的出现,会使得HP刷呈现极强的抗污性.另外,当体系中水蒸气浓度增加、水合相互作用增强时,增加的P-W氢键将平衡HP单体之间的偶极-偶极相互作用,使得结节解开,聚合物链伸展.我们的理论结果符合实验观测,由此表明,P-W氢键效应,以及HP单体之间的偶极-偶极相互作用决定着HP刷的构象转变和结构特性,刷内出现的两性离子聚合物链内单体间的结节和链间单体结节状凝胶结构,是两性离子聚合物刷呈现较强抗污性的本质特性.

疏水化多糖自聚集系统的制备方法及其形成机制分析

天然多糖作为一种安全、无毒和有效的递送载体材料近年来得到广泛的关注,但两亲性和聚集能力缺乏、空间结构难控及易失稳等缺点制约了其应用,而适度疏水化处理能使多糖分子在高级结构上发生巨变,赋予其更多的结构调控性和应用可能性。该文系统梳理了近5年疏水化多糖的研究进展,主要总结了通过疏水化多糖制备各种自聚集系统(主要包括胶束、反胶束、聚合物囊泡和水凝胶等)的方法路径,分析了其形成的前提条件和分子机制。结果发现可通过选择疏水化多糖种类及其制备方法定制其自聚集系统的结构、粒径大小和形貌等特性,以期实现特定场所应用,为疏水化多糖自聚集体及其递送系统的设计、制备和应用提供基础与依据。

XeCl(308nm)准分子紫外激光对生物大分子酵母甘露聚糖分子结构的辐照效应

激光在农业和医疗等方面已有广泛应用,并且取得增产和一定疗效,但也有费介现象(暂称后继效应或潜在效应)。激光辐照生物体虽然是局部的有限时间,但对由多种生物大分子组成的生物体的影响可能是综合的。为了探索激光生物学效应的分子机理,以便进一步认识和掌握激光的生物学效应,对激光直接辐照有生物活性的生物大分子—酵母甘露聚糖产生的效应进行电镜扫描观察和紫外及红外光谱法分析研究。实验结果表明:308 nm激光(单脉冲25 m J,33.3 m J^34.4 m J,脉冲频率2次/s)无论是固定辐照时间(45 s)变化样品所置距离,或反之固定样品所置距离(290 mm)改变辐照时间为15 s、30 s、45 s或60 s,都能引起受照样品的结构(构象)变化,特别是糖分子结构中富含的-OH-、CH-OH、-C-O-C--、N-C=O-、C=O等结构部件处的IR谱线对激光能量变化影响敏感。它们既是糖分子内或分子间形成氢键和糖苷键的结构基础部件,又是甘露聚糖(M an-nan)糖基化其他生物大分子进而影响它们在生物信息流中作用的重要结构部件。结果显示糖在激光生物效应中起了不可忽视的作用,这为综合探索激光生物效应分子机理和糖在生物信息传递中的作用提供了重要线索,为选择甘露聚糖作为生物导弹载体提供了参考依据。

三足型三{2-[(5-X-2-羟基苯亚甲基)亚胺]乙基}胺化合物(X=H,Cl)的合成、表征及结构

三(2-氨基乙基)胺分别与水杨醛、5-氯水杨醛反应,合成两个三{2-[(5-X-2-羟基苯亚甲基)亚胺]乙基}胺化合物,X:H(1),Cl(2)。经红外光谱、核磁共振1 H和13 C谱表征,X-射线衍射方法测定其晶体分子结构,化合物(1)为单斜晶系,P2(1)/c空间群;化合物(2)三斜晶系,P-1空间群。化合物(1)和(2)具有三足型结构,它们的构象分析表明,螺旋桨型结构的体系能比三足型结构更低,它们的体系能能差ΔE:969.57kJ/mol (1),926.00kJ/mol(2),非键作用能差ΔE:125.25kJ/mol(1),166.14kJ/mol(2),因此,螺旋桨型比三足型结构更稳定。为三足型配体与金属的配位化学研究提供有益的参考。

试论生物信息流与激光生物效应的相关性——激光生物效应分子机理研究

为了探索激光生物学效应的分子机理,以便更好的掌控和利用激光生物效应,用XeCl(308 nm)准分子紫外激光以相同变化的激光参量直接辐照有生物活性的生物大分子BTG DNA、BSA(v)蛋白质和糖Mannan。实验结果分析告知:电镜法观察到受辐照的三类生物大分子的表观结构、构象(含结构信息)和光谱法(IR、Vis-UV、FR、CD)分析指出生物大分子的内在结构部件的相关的特征峰的峰位、峰值都受影响,其变迁都与激光参量的变化相呼应;与三类生物大分子中分子内、分子间沟通与信息传递相关的氢键、糖苷键等的形成与否的类似或相同的结构部件(如-C-H、-N-H、-CH-OH、-C-O、-C=O等)其特征峰的变迁都更敏感于激光参量的改变。激光辐照生物体时,激光似生物信号分子通过它的能量以粒子性、电磁波相干性影响生物大分子的分子结构、构象(含结构信息)的稳定性、增加分子内、分子间相互沟通、信息传递,亦增加了结构部件的被修饰的可能性。进而影响着生物信息流的流量与流向和细胞信号转导的协同与整体表达,产生相应的生物效应。掌握获得功能生物大分子结构构象信息与使用适宜的激光参量的相关的关系值(阈值)是重要的关键。

硬脂酸亚甲基面外弯曲振动变温FT-IR光谱研究

在293～393 K温度范围内,分别采用傅里叶红外光谱、二阶导数红外光谱、四阶导数红外光谱及去卷积红外光谱测定硬脂酸亚甲基面外弯曲振动(ωCH2),来进一步研究温度对于硬脂酸脂肪链构象的影响。实验发现:在1180～1320cm-1范围内,硬脂酸ωCH2存在"第一特征谱带"和未见文献报道的"第二特征谱带"。硬脂酸脂肪链由全反式有序构象到无序构象的改变的临界温度为353～358K,并进一步研究了温度对于硬脂酸ωCH2红外吸收峰强度的影响。

静电纺丝素/壳聚糖纳米纤维的研究

以质量分数为98%的甲酸为溶剂,丝素和壳聚糖以不同质量分数及比例共混制备纺丝液进行静电纺丝,并用扫描电镜观察其形态结构。结果表明:当丝素和壳聚糖溶液质量比为70/30,两者质量分数分别为13%～17%和3%～5%时,都能获得连续纤维;当丝素和壳聚糖溶液质量分数分别为17%和4%,两者质量比高于50/50时,均能静电纺得连续纤维,纤维直径随壳聚糖含量的增加而减小,质量比低于50/50时,制成的纳米纤维中含有壳聚糖颗粒。采用红外光谱法测定了丝素/壳聚糖纳米纤维的结构,结果表明:壳聚糖与丝素之间有相互作用,经乙醇处理促进了丝素构象转变为β结构。

乙肝病毒外膜大蛋白的临床检测及其意义

通过对乙型肝炎病毒外膜大蛋白(Hepatitis B virus large surface protein,HBV-LP)结构、功能的阐述,分析其检测技术的发展历程,让临床医生更深层次的了解其临床意义,为今后广泛的应用于临床做好铺垫。HBV基因组的S区分为preS1、preS2和S基因3段。HBV-LP即由S、Pre-S1及Pre-S2基因区所编码。大蛋白的前S区具有独特的立体构象拓扑结构,是HBV-LP发挥多种功能作用的依赖性结构。拓扑结构决定其具有反式激活作用。在HBV DNA阴性的患者中,HBV-LP阳性可能是肝内病毒继续复制和抗病毒治疗不彻底的标志。使用酶联免疫定量方法检测HBV-LP与HBV DNA的检测有良好一致性,是反映HBV复制活跃的可靠指标,可以作为HBV感染、复制和乙肝患者诊断、治疗和预后的重要标志物,具有较高的临床应用价值。

The Study on Tourist Destination Tourism Image Perception and Evaluation in Xi'an City

[Objective] The aim was to explore the tourist destination image measurement method, and have an empirical study on Xi＇an City. [Method] With combination of non-structural and structured approach to design questionnaires, tourism image of Xi＇an was explored using the SPSS software from both the qualitative and quantitative analyses. [Result] Xi＇an tourism images serve a heritage historical monuments atmosphere with the Terracotta Warriors, City Wall, Big Wild Goose Pagoda,Huaqing Hot Springs, presenting a positive feeling among tourists in general. In the dissemination of travel, tourism infrastructure construction, tourism transportation,travel services have negative effects on the image of Xi＇an tourism. [Conclusion]The evaluation on the tourism resources is highly spoken of by tourists than the scenic spot, indicating that despite high visibility of tourism resources in Xi＇an, it has not formed strong core competitiveness and a complete tourism industrial chain. It is necessary to take the right marketing strategies to enhance tourist familiarity to Xi＇an. Tourists demands, therefore, should be well considered in developing Xi＇an scenic spots and new tourism products and projects be focused on to improve tourists＇ satisfaction.

Synthesis and Crystal Structure of ( Z)-4-( p- Bromophenylthio)-3-( p-nitrobenzoyloxy)-3-buten-2-one

A new enone (CH 3CO C( p NO 2C 6H 4COO)=CH S C 6H 4( p Br) 5, C 17 H 12 NBrO 5S, M r =422.25) was synthesized and its crystal structure was determined by X ray diffraction method. The crystal belongs to the monoclinic system, space group P2 1/c with a=6.4121(9), b=12.804(1), c=20.998(2) , β=94.884(9)°, V=1717.1(3) 3, Z=4, D c =1.633 g/cm 3, μ (Mo Kα )=2.542 mm -1 , F( 000)=848. Final R =0.0428 and wR =0.0916 for 3335 reflections with I>2σ(I) . The title compound exists as Z isomer with p bromothiophenolate and o nitrobenzoate groups cis arranged around asymmetrical centre. This observation suggests that the substitution of thiophenolate for bromine is a stereoselective step.

Crystal Structure and Conformation of 2'-C-Ethoxy-3',5'-O-(tetraisopropyldisiloxane-1,3-diyl)uridine

The title compound, C23H42N2O8Si2, Mr=530.77, crystallizes in the monoclinic system, space group P21, with a=10.577(5), b=10.528(2), c=13.374(5)?, (=100.63(3)(, V=1461(2)?3, Z=2, Dx=1.207g/cm3, ((MoK()=0.71073?, (=1.590mm-1, T=299(1K, F(000)=572, R=0.070 and Rw=0.075 for 1232 observed reflections with I (3((I). The analysis result indicates that the configuration of the title compound at C(2() is S. In the crystal state the molecule has anti- conformation about glycosidic bond with the torsion angle -126.96(. The sugar ring is puckered with C3(-endo-C4(-exo, and the conformation of the C(4()-C(5() bond is +sc.

Ordered Toroid Structures of Nanoparticles in Self-attractive Semiflexible Polymer/Nanoparticle Composites

By employing dynamic Monte Carlo simulations, we investigate a coil-to-toroid transition of self-attractive semiflexible polymers and the spatial distributions of nanoparticles in self- attractive semiflexible polymer/nanoparticle composites. The conformation of self-attractive semiflexible polymers depends on bending energy and self-attractive interactions between monomers in polymer chains. A three-stage process of toroid formation for self-attractive semiflexible chains is shown： several isolated toroids, a loose toroid structure, and a compact toroid structure. Utilizing the compact toroid conformations of self-attractive semiflexible chains, we can control effectively the spatial distributions of nanoparticles in self-attractive semiflexible polymer nanocomposites, and an unconventional toroid structure of nanoparti- cles is observed.

Crystal and Molecular Structure of OMPCTF

The title compound C_(28)H_(48)O_4 (M_r=448. 8) crystallizes in the triclinic, space group P1 with a=12. 909(5) , b=10. 422(4) , c=11. 052(4) A, α=108. 35 (3), β=100. 07(3), γ=70. 06(3)°, Z=2, V=1322. 9(8) A￣3,109. D_c=1. 13 gcm￣(-3), F(000)=496, μ(MoKa)=0. 80cm￣(-1). The final R=0. 067 and R_w=0. 074 for 1652 observed independent reflections (I≥3σ(I)). The conformation of the molecule is rather unusual , and there is not any symmetry element involved in it.The four units are different from each other in bond lengths and bond angles. The distances between two separate oxygen atoms are 5. 77 and 4. 25 A, respectively , and those between two adjacent oxygen atoms average 3. 59 A.

Computational Exploration of Conformations of Glycine-Arginine and a Deduced Model on Global Minimum Configurations of Dipeptides in Gas Phase

An extensive computational study on the conformations of gaseous dipeptide glycine- arginine, GlyArg, has been performed. A large number of trail structures were generated by systematically sampling the potential energy surface （PES） of OlyArg. The trial structures were successively optimized with the methods of PM3, HF/3-21G＊, BHandHLYP/6-31G＊ and BHandHLYP/6-311＋＋G＊＊ in order to reliably find the low energy conformations. The eonformational energies were finally determined with the methods of BHandHLYP, cam- B3LYP, B97D, and MP2 using the basis set of 6-311＋＋G（3df,3pd）. The results establish firmly that gaseous GlyArg exists primarily in its canonical form, in sharp contrast with ArgGly that adopts the zwitterionic form. Important data such as the rotational constants, dipole moments, vertical ionization energies, temperature distributions and IR spectra of the low energy conformers are represented for the understanding of the future experiments. Moreover, considering the global minima of all amino acids and many dipeptides, combined with the hydrophobicities of amino acids, a model predicting whether the global minimum configuration of a dipeptide is canonical or zwitterionic is developed.

Conformations and Metal Ion Affinities of Glutamine Binding with Alkali and Alkaline Earth Metal Cations： an ab initio Study

Conformations and reaction energetics are important for understanding the interactions be- tween biomolecules and metal ions. In this work, we report a systematic ab initio study on the conformations and metal ion affinities of glutamine （Gln） binding with alkali and alkaline earth metal ions. An efficient and reliable method of searching low energy conformations of metalated Gln is proposed and applied to the complexes of Gln.Gln.M^＋/＋＋（M＋/＋＋=Li^＋、Na^＋、K^＋、Rb^＋、Cs^＋、Be^＋＋、Mg^＋＋、Ca^＋＋、Sr^＋＋ and Ba^＋＋）.. In addition to all conformers known in literatures, many new important conformations are located, demonstrating the power of the new method and the necessity of the conformational search performed here. The metal coordination modes, relative energies, dipole moments, and equilibrium distributions of all important conformations of Gln.M^＋/＋＋ are calculated by the methods of B3LYP, BHandHLYP, and MP2. IR spectra and metalation enthalpies and free energies are also presented and compared with the available experiments. The results form an extensive database for systematic examination of the metalation properties of Gln.

氨基肽酶N的结构与功能研究进展

氨基肽酶N (APN)是一种含有Zn2+的膜结合型外肽酶,属于金属蛋白酶M1家族,相对分子质量约为150 kDa,在自然界广泛存在,有膜结合型和可溶型两种形式。作为一种"兼职酶",APN通过酶依赖性和非酶依赖性途径在哺乳动物体内参与多种生理病理活动。该文简述了APN的发现和分类,以及哺乳动物APN的晶体结构和胞外区的三种构象变化,并从肿瘤标志物、病原受体和免疫三个方面对APN的主要功能进行分类汇总,旨在解析APN的相关病理机制,为靶向APN的疾病治疗及药物开发方案提供基础资料。

拉曼光谱技术在聚合物研究中的应用进展

拉曼光谱可以提供分子的振动信息,对于聚合物分子链的构象和链间的相互作用非常敏感,能够提供聚合物固体、薄膜或溶液的物理化学特性信息,如聚合物的结构单元、空间构型、晶态结构、分子链的物理构象或分子链子链和侧基在界面间或在各向异性材料中的排列等链取向信息等。因此拉曼光谱作为一种原位无损检测技术,其衍生出的表面增强拉曼光谱技术(Surface-enhanced Raman Scattering,SERS)、变温拉曼光谱技术、共焦显微拉曼光谱技术(Confocal Raman Microscopy,CRM)、拉曼Mapping成像技术和共振拉曼散射技术(Resonance Raman scattering,RRS)等,广泛应用于物理、化学和生物医学等领域。本文从拉曼光谱的基本理论基础、拉曼光谱技术及其在聚合物研究中的最新应用进展等方面进行综述,以探索扩展拉曼光谱技术在高分子物理与化学领域中许多问题,如分子链的构象结构、分子链的结晶行为、分子链的扩散运动和共混体系相态结构变化等方面的应用。

Physicochemical bases for protein folding,dynamics,and protein-ligand binding

Proteins are essential parts of living organisms and participate in virtually every process within cells. As the genomlc sequences for increasing number of organisms are completed, research into how proteins can perform such a variety of functions has become much more intensive because the value of the genomic sequences relies on the accuracy of understanding the encoded gene products. Although the static three-dimensional structures of many proteins are known, the functions of proteins are ulti- mately governed by their dynamic characteristics, including the folding process, conformational fluctuations, molecular mo- tions, and protein-ligand interactions. In this review, the physicochemical principles underlying these dynamic processes are discussed in depth based on the free energy landscape （FEL） theory. Questions of why and how proteins fold into their native conformational states, why proteins are inherently dynamic, and how their dynamic personalities govern protein functions are answered. This paper will contribute to the understanding of structure-function relationship of proteins in the post-genome era of life science research.