蛋白质结构和功能的紫外共振喇曼光谱研究

紫外共振喇曼光谱技术是研究复杂大分子结构的有力工具。结合作者在美国Pittsburgh University期间所做的工作，介绍了用紫外共振喇曼光谱研究肽和蛋白质结构与功能的现状和进展，N-methylacetamide和glycyglycine水溶液光化学异构过程的紫外共振喇曼光谱研究，简述了紫外共振喇曼光谱实验技术要点。本文还跟踪国际最新研究成果，介绍了利用紫外共振喇曼光谱技术研究蛋白质的折叠和去折叠过程。     

Co掺杂ZnO纳米棒的共振拉曼光谱和发光特性

采用X射线衍射(XRD)和透射电子显微镜(TEM)手段对微乳液法合成的Zn0.9Co0.1O纳米棒进行了表征.通过室温下的共振拉曼光谱和光致发光光谱手段,研究了所合成纳米材料的共振拉曼光谱和发光特性,并与体相ZnO的研究结果对比,发现合成的材料具有四阶声子紫外共振拉曼散射,而体相材料只有两阶,并观察到在紫外和可见区域所...     

1,1''联萘-2,2''-二胺拉曼和红外光谱的实验和DFT计算研究

实验测量了1,1''-联萘-2,2''-二胺（BINAM）的红外吸收光谱、可见光激发普通拉曼光谱、紫外共振拉曼光谱.用电子密度泛函方法计算了BINAM的基态几何构型、振动频率、普通拉曼和近共振拉曼强度.通过实验和理论计算对比,对所得红外和拉曼提出了详细的指认,并且分析了各振动模式的特征.BINAM的紫外共振拉曼光谱与普通拉曼光谱相比较,发现有若干拉曼谱带出现了选择性共振增强.基于共振拉曼强度分析,讨论了BINAM可能的激发态几何结构的变形.     

中国光谱成就奖

正李灿院士:在催化光谱研究领域做出了杰出贡献。特别是发展了原位红外光谱、紫外共振拉曼光谱、短波长手性拉曼光谱和光电成像光谱技术等,解决了多相催化、手性催化和光(电)催化的若干重大科学问题。     

小型紫外拉曼光谱仪

紫外拉曼光谱技术具有拉曼本征散射效率高,受杂散光干扰小等优点,在爆炸物、污染物以及农药残留现场检测等领域有着广阔的应用前景。然而,目前市场上常见的小型或者便携式拉曼光谱仪均采用可见或者近红外激光作为激发光源。本研究在实验室具有自主知识产权的紫外可见共振拉曼光谱仪的基础上,设计了小型紫外拉曼光谱仪,光谱仪采用透镜作为光谱仪的准直镜和聚焦镜,有效减小了慧差造成的影响,实现了高分辨率和宽光谱范围的测试。     

拉曼光谱检测生物大分子损伤的研究进展

拉曼光谱是基于拉曼散射效应而发展起来的一种光谱分析技术,体现的是分子的振动或转动信息。由于拉曼光谱技术与常规化学分析技术相比,具有对样品无损、样品制备简单和所需样品量少等特点,广泛用于生物大分子结构变化的研究。拉曼光谱不仅可以用于蛋白质、核酸和脂类等生物大分子损伤的快速检测,而且可以用于癌症的诊断与手术治疗。通过对比正常组织与癌变组织的拉曼光谱,可以找到两种组织特征吸收峰的差异,从而为癌症的最终确诊和确定肿瘤切除范围提供重要信息。文章综述了拉曼光谱检测生物大分子损伤的研究进展,介绍了利用表面增强拉曼光谱、傅里叶变换拉曼光谱和紫外共振拉曼光谱等技术在检测蛋白质二级结构、膜脂及DNA损伤中的应用,并展望了未来拉曼光谱技术的发展前景。     

共振拉曼光谱技术应用综述

拉曼光谱是提供物质结信息的强有力工具。但由于拉曼散射信号弱,灵敏度低,因此应用范围受到限制。而在共振拉曼光谱(RRS)中,由于激发光源频率落在分子的某一电子吸收带内,分子吸收光子向电子激发态的跃迁变成了共振吸收,因此对入射光的吸收强度大大增加。与常规拉曼光谱相比,RRS能够提高信号强度的106倍。因此,RRS检测技术以其更高的灵敏度和选择性而具有更广的应用,特别是在生物学及医学等领域。如：(1)生物基质中的类胡萝卜素和叶绿素等色素分析;(2)细胞、蛋白质和DNA等有机物研究以及一些临床疾病诊断。RRS可以得到在常规拉曼光谱中隐藏的、更为重要的分子结构信息。RRS总是在很低的浓度下测试,且共振拉曼增强的谱线是属于产生电子吸收的基团,这对于有色物和生物样品尤为重要。因为很多这类样品的活性部位接近于生色基团,且研究对象往往是生物大分子的某一部分,所以在研究生物物质的结构和功能的关系时,RRS起着重要作用。近年来,由于光谱技术的发展使得RRS检测技术得到创新与延伸,如液芯光纤共振拉曼光谱和透射共振拉曼光谱等新技术的应用。通过对近几年有关RRS技术应用的原始论文、数据和主要观点进行归纳整理与分析提炼,介绍了RRS这一专题的历史背景和研究现状,分别对共振拉曼光谱的色素检测、生物检测和爆炸物检测等应用领域展开详细的综述,并介绍了相关新技术的发展应用。随着光谱技术的快速发展,RRS必将在科研领域拥有其他光谱技术不可取代的重要地位。     

远程紫外拉曼光谱检测技术研究进展

远距离检测主要用于人类不宜或不易接触的物品检测,紫外拉曼光谱法是一种比较有效的远距离危险物品检测方法,在反恐、禁毒和食品安全等领域具有广泛的应用前景。本文在分析远程拉曼光谱检测技术基本原理的基础上,总结了紫外拉曼光谱检测技术的优势,对远程紫外拉曼光谱检测技术的现状进行综合分析。从激光器发射、光学接收系统、光谱接收、光谱处理等方面分析了不同模块关键技术及研究现状,分析了远程紫外拉曼光谱检测技术的研究难点和发展趋势。     

线性多烯分子的共振拉曼光谱

线性多烯分子是重要的光电材料,它还具有光采集、 光防护、 防癌、 抗癌功能,也是物理学、 化学理论研究的理想分子。 共振拉曼光谱是研究线性多烯分子最有力的工具。 本文总结了线性多烯分子共振拉曼光谱的特征及其与分子结构的关系,包括：电子光谱(紫外-可见吸收光谱)、 拉曼光谱的性质及与外场的关系;电子能隙对碳碳原子振动的调制作用;给出几个实验结果：温度降低、 溶剂密度增加、 溶液浓度降低等会使线性多烯分子结构有序增加,π电子能隙减小,使紫外-可见吸收光谱红移;π电子离域扩展,有效共轭长度增加,拉曼活性提高,拉曼光谱红移,拉曼截面增加。 振幅模型是研究线性多烯分子较理想的模型。     

前期共振拉曼效应在微量分析中的应用

本文讨论了前期共振拉曼光谱法(Pre-resonance Raman Spectroscopy,以下简称PRRS)检测在大气颗粒物中多环芳烃硝基化合物的能力。鉴于硝基芳烃在环境科学与生物科学中的重要性,选择了若干对位取代硝基苯衍生物及多环芳烃硝基化合物,它们都以硝基苯为其基本结构。首先测定这些化合物的紫外吸收光谱,其最大吸收波长在260—400nm范围。根据前文,用488.0nmAr~+激光作拉曼激发源,这些化合物都可能产生前期共振拉曼效应,从而可以用来进行微量分析。利用共振拉曼效应进行微量分析,经常遇到试样所产生的萤光背景干扰问题。这种背景往往超过拉曼光谱强度,成为拉曼光谱测定中的主要干扰。基干拉曼效应和萤光效应激发态寿命之不同而发展起来的克服萤光干扰的脉冲技术,由于价格昂贵,技术复杂,对于一般光谱实验室来说,目前还不能普遍实用。     

Photochemical sensitization and magnetic field effect on aerosol particle formation from a gaseous mixture of glyoxal and acrolein

Under light irradiation at 435.8 nm with a medium pressure mercury lamp, pure acrolein (AC) vapour does not produce any deposits, but a gaseous mixture of glyoxal (GLY) and AC produced sedimentary aerosol particles. The nucleation process of the aerosol particles was investigated by measuring He-Ne laser light intensity scattered by the aerosol particles as formed under light irradiation at 435.8 nm. From the dependence of the scattered light intensity on the partial pressure of GLY, it was found that electronically excited GLY in the nπ? state initiated chemical reactions with AC leading to nucleation of the aerosol particles. Magnetic field effects on the nucleation process were measured for a gaseous mixture of GLY and AC. With the application of a magnetic field of 5.3 kG, the nucleation reaction was accelerated, and the convection of the gaseous mixture was changed due to greater heat release during nucleation reaction between GLY and AC. The magnetic field effect on the gaseous mixture is discussed based on the photochemical behaviour of GLY.     

Photochemical sensitization and magnetic field effect on ultrafine particle formation from a gaseous mixture of glyoxal and carbon disulphide

Under light irradiation at 435.8 nm with a medium-pressure mercury lamp, a gaseous mixture of glyoxal (GLY) and carbon disulphide (CS₂) produced sedimentary aerosol particles at the initial stage of light irradiation. The nucleation process of the aerosol particles was investigated by measuring He-Ne laser light intensity scattered by the aerosol particles as formed under light irradiation at 435.8 nm. From the dependence of the scattered light intensity on the partial pressure of GLY, it was found that electronically excited GLY in the n-π* state initiated chemical reactions with CS₂ leading to nucleation of the aerosol particles. An external magnetic field effect on the nucleation process was measured for a gaseous mixture of GLY and CS₂. With the application of a magnetic field of 5.1 kG, the nucleation reaction was accelerated and the convection of the gaseous mixture was changed. The magnetic field effect on the gaseous mixture is briefly discussed in comparison with the results obtained from a gaseous mixture of GLY and acrolein recently reported by us.     

DNA tertiary structure and changes in DNA supercoiling upon interaction with ethidium bromide and gyrase monitored by UV resonance Raman spectroscopy

The tertiary structure of DNA is important for many of its biological functions. In this work supercoiled and relaxed forms of purified plasmid DNA pBR322 in dilute aqueous solutions are investigated by means of UVRR spectroscopy to assess changes in B‐DNA conformation. Spectral variation in the CO and exocyclic NH₂ vibration above 1600 cm⁻¹ indicate changes in hydrogen bonding. A minor shift of the CN stretching mode of adenosine and guanosine at 1487 cm⁻¹ supports these findings. Changes in ribose conformation are visible in the spectral region 1320–1360 cm⁻¹ by vibrational coupling of the ribose pucker to the vibrations of the purine and pyrimidine bases. The intercalating phenanthridinium drug ethidium bromide is known to reduce the negative supercoiling of DNA. This change in DNA topology is reflected in variations of the UVRR marker bands of DNA identified above. Principal component analysis helped to extract the features of interest from the complex spectra of the intercalation complex. Within the bacterial cells the change in DNA topology is achieved by the action of topoisomerases. In this work, the DNA‐binding subunit GyrA of the enzyme gyrase was extracted from E. coli and applied to relaxed and supercoiled pBR322. The observed changes in the vibrational signature of the relaxed DNA in the presence of GyrA indicate a change of topology towards the supercoiled form. With already supercoiled DNA no further change in DNA topology is observed. Copyright © 2007 John Wiley & Sons, Ltd.     

UV resonance Raman study of cation–π interactions in an indole crown ether

UV resonance Raman (UVRR) spectroscopy is used to probe changes in vibrational structure associated with cation–π interactions for the most prevalent amino acid π–donor, tryptophan. The model compound studied here is a diaza crown ether with two indole substituents. In the presence of sodium or potassium sequestered in the crown ether, or a protonated diaza group on the compound, the indole moieties participate in a cation–π interaction in which the pyrrolo group acts as the primary π‐donor. Systematic shifts in relative intensity in the 760–780 cm⁻¹ region are observed upon formation of this cation–π interaction; we propose that these modifications reflect shifts of the delocalized, ring‐breathing W18 and hydrogen‐out‐of‐plane (HOOP) vibrational modes in this spectral region. The observed changes are attributed to perturbations of the π‐electron density as well as of normal modes that involve large displacement of the hydrogen atom on the C2 position of the pyrrole ring. Modest variations in the UVRR spectra for the three complexes studied here are correlated to differences in cation–π strength. Specifically, the UVRR spectrum of the sodium‐bound complex differs from those of the potassium‐bound or protonated‐diaza complexes, and may reflect the observation that the C2 hydrogen atom in the sodium‐bound complex exhibits the greatest perturbation relative to the other species. Normal modes sensitive to hydrogen‐bonding, such as the tryptophan W10, W9, and W8 modes, also undergo shifts in the presence of the salts. These shifts reflect the strength of interaction of the indole N H group with the iodide or hexafluorophosphate counteranion. The current observation that the W18 and HOOP normal mode regions of the indole crown ether compound are sensitive to cation–pyrrolo π interactions suggests that this region may provide reliable spectroscopic evidence of these important interactions in proteins. Copyright © 2010 John Wiley & Sons, Ltd.     

Structure elucidation of fluorescent H1 antihistamines by ultraviolet resonance Raman spectroscopy: solvent structures of tripelennamine and mepyramine

Ultraviolet Resonance Raman (UVRR) spectroscopy—a Raman technique that combines high sensitivity with high selectivity and does not suffer from background fluorescence—is applied to the fluorescent H₁ antihistamines tripelennamine (TRP) and mepyramine (MEP) in aqueous solution to elucidate their molecular structure as a function of pH. In a previous investigation of these compounds (C. Tardioli, G. Gooijer G. van der Zwan, J. Phys. Chem. B, 113 , (2009), 6949), the presence of gauche conformers caused by intramolecular interaction of the protonated alkylamine tail with the pyridine nitrogen was assumed to explain the pH dependence of the fluorescence properties. In order to validate this assumption, use is made of the resonant excitation of the aminopyridine chromophore in TRP and MEP. In that way, structural information associated with the vibrations of that moiety can be obtained, and the changes it undergoes upon protonation can be monitored. Assignment of the vibrations was achieved with the help of a number of other compounds, and quantum chemical calculations. N,N‐Dimethylaminopyridine (2DMP) and its mono‐protonated form (2DMPH⁺) were investigated, since this molecule was shown to have optical properties closely resembling those of the aminopyridine moiety in TRP and MEP. Assignment of the vibrations of 2DMP was accomplished by comparison with the resonance Raman spectra of two other reference structures, 2‐aminopyridine and dimethylaniline—for which ordinary Raman data are available—and by Gaussian calculations. UVRR spectra of TRP and MEP could be readily interpreted on the basis of vibrational assignments of the parent chromophores, i.e. 2DMP and 2DMPH⁺. Vibrations of the aminopyridine chromophore in TRP and MEP at neutral pH, where the aminoalkyl chain is protonated, are modified when compared to the vibrational pattern recorded for a fully neutral molecule in alkaline solution. This implies an electronic redistribution in the ring originating from internal hydrogen bonding between the aminoalkyl tail and the aminopyridine chromophore. Copyright © 2010 John Wiley & Sons, Ltd.     

Detection of bacteria aided by immuno‐nanoparticles

Magnetic immuno‐nanorice particles were used for the capture and detection of Escherichia coli (E. coli) bacteria. The selectivity of the method was attained by attaching a specific anti‐E. coli antibody on the surface of the nanorice, binding exclusively to E. coli. The antibody attachment to the nanorice (60% sorption efficiency) took place through protein‐A molecules (82% uptake). Once E. coli was captured, the immuno‐nanorice‐bacteria complex was separated from the solution using the magnetic property of the nanorice. The detection of bacteria sorbed onto the immuno‐nanorice was accomplished using the ultra‐violet resonance Raman (UVRR) method, detecting single bacterial cells. Specific information concerning the aromatic residues tyrosine (Tyr), phenylalanine (Phe) and tryptophan (Trp) was derived. The discriminant function and cluster hierarchical analysis confirmed the specific and reliable bacteria‐detection capabilities. Copyright © 2007 John Wiley & Sons, Ltd.     

Effects of cryoprotectant agents and equilibration methods on developmental competence of porcine oocytes

Chemical toxicity of cryoprotectants to in vitro developmental competence of porcine oocytes was examined. In vitro-matured oocytes were exposed to 40 percent ethylene glycol (EG), glycerol (GLY), or 1,2-propanediol (PD), fertilized with spermatozoa, and cultured for 8 days. Compared to treatment with other cryoprotectants, exposure to EG resulted in the development of significantly more blastocysts, but the rate was significantly lower than that of non-exposed control oocytes. In vitro-matured oocytes were also equilibrated in 40 percent EG by 3 multi-step methods, after which their developmental competence was evaluated. The rate of blastocyst development was higher in the 4-step method than in the 2- and 3-step methods of equilibrium. These results indicate that cryoprotectants and equilibration methods affect the developmental competence of porcine oocytes and that EG may be a superior cryoprotectant for vitrification of these cells.     

Preparation and characterization of porous DVB copolymers and their applicability for adsorption (solid-phase extraction) of phenol compounds

Using DVB, three new porous copolymers in the form of microspheres were prepared, characterized and used as adsorbents for phenol and its chlorinated derivatives. As the monomers: 4,4′-bis(maleimidodiphenyl)methane (BM), 2,3-bis(2-hydroxy-3-methylacryloyloxy-propoxy)naphthalene (2,3-NAF) and 2,3-epoxypropyl methacrylate (GLY) were used. All the studied materials were synthesized under the same conditions by means of suspension copolymerization. The DVB copolymers were characterized by elemental analysis, FTIR spectroscopy, TG and DSC analyses and N₂ sorption. The off-line solid-phase extraction method (SPE) was used to estimate sorption properties of the copolymers. The results show that the newly obtained materials are mesoporous but their shape of pores and chemical structures are different. BM-DVB and GLY-DVB are characterized by slit-shaped pores and wide pore size distribution. 2,3-NAF-DVB also possesses slit pores but distribution of pore size is narrower. Of those studied BM-DVB is the most interesting material. It has good sorption properties and heat resistance.     

基于支持向量机、支持向量回归和分子对接的CYP450 1A2抑制剂的发现研究

支持向量机,支持向量回归和分子对接的计算方法已广泛应用于化合物的药理活性计算。为了提高计算的准确性和可靠性,拟以细胞色素P450酶1A2为研究载体,运用建立的联合SVM-SVR-Docking计算模型预测潜在的CYP1A2抑制剂。其中,建立的最优SVM定性模型训练集,内部测试集和外部测试集的准确率分别为99.432%,97.727%和91.667%。最优SVR定量模型训练集和测试集的R和MSE分别为0.763,0.013和0.753,0.056。实验表明两个模型具有较高的准确性和可靠性。通过对SVM和SVR模型结果的比较分析,发现连接性指数、分子构成描述符和官能团数目等分子描述符可能与CYP1A2抑制剂的辨识和活性预测密切相关。随后利用分子对接技术分析化合物与CYP1A2的结合构象及相互作用的稳定性。形成氢键相互作用的关键氨基酸包括THR124,ASP320;形成疏水相互作用的关键氨基酸包括ALA317和GLY316。所获得模型可用于天然产物化学成分中CYP1A2潜在抑制剂的活性计算及其介导的药物-药物相互作用预测提供理论指导,也为合理联合用药提供一定参考。共获得20个对CYP1A2具有潜在抑制活性的化合物。部分结果与文献结果相互印证,进一步说明了模型的准确性和联合计算策略的可靠性.