共查询到20条相似文献,搜索用时 15 毫秒
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吖啶橙-罗丹明6G荧光共振能量转移及其罗丹明6G荧光猝灭法测定蛋白质 总被引:16,自引:0,他引:16
研究了吖啶橙(AO)与罗丹明6G(R6G)之间能量转移的最佳条件。在pH=7.20的Tirs-HCl缓冲溶液,十二烷基苯磺酸钠介质中,AO-R6G能够发生有效能量转移,使R6G荧光增强。蛋白质的加入使R6G荧光猝灭,以此建立了利用AO-R6G荧光共振能量转移间接测定蛋白质的新方法。牛血清白蛋白、人血清白蛋白工作曲线线性范围分别为1.0~31和1.0—30mg/L;检出限分别为0.32和0.33mg/L;平行6次测定相对标准偏差为1.1%~2.0%;回收率为96.7%~103.2%。此方法的稳定性好,选择性高,用于人血清试样中总蛋白含量的测定,与常用的双缩脲法基本一致。 相似文献
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Zakharov Alexander V. Vogt Natalja Shlykov Sergey A. Giricheva Nina I. Vogt Jürgen Girichev Georgiy V. 《Structural chemistry》2003,14(2):193-197
The structural investigation of molecules in the vapor over neodymium tribromide was performed by synchronous gas-phase electron diffraction and mass spectrometric (GED/MS) experiments at 1110(10) K. Besides the monomeric molecules (NdBr3), a small amount (0.7%) of the dimer (Nd2Br6) was detected. For NdBr3, the thermal-average bond length r
g
(Nd–Br) of 2.675(6) Å was determined. The equilibrium structure was estimated to be planar (or nearly planar) with r
e
(Nd–Br) of 2.659(7) Å. Three vibrational frequencies were estimated using the GED data: 1 = 193 cm–1, 2 = 35 cm–1, 4 = 41 cm–1. The structural parameters of Nd2Br6 could not be refined and were constrained at the estimated values during the analysis. 相似文献
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Dr. Mathias Paul Dr. Katrin Peckelsen Thomas Thomulka Dr. Jonathan Martens Dr. Giel Berden Prof. Dr. Jos Oomens Dr. Jörg-M. Neudörfl Dr. Martin Breugst Prof. Dr. Anthony J. H. M. Meijer Prof. Dr. Mathias Schäfer Prof. Dr. Albrecht Berkessel 《Chemistry (Weinheim an der Bergstrasse, Germany)》2021,27(8):2662-2669
Breslow intermediates (BIs) are the crucial nucleophilic amino enol intermediates formed from electrophilic aldehydes in the course of N-heterocyclic carbene (NHC)-catalyzed umpolung reactions. Both in organocatalytic and enzymatic umpolung, the question whether the Breslow intermediate exists as the nucleophilic enol or in the form of its electrophilic keto tautomer is of utmost importance for its reactivity and function. Herein, the preparation of charge-tagged Breslow intermediates/keto tautomers derived from three different types of NHCs (imidazolidin-2-ylidenes, 1,2,4-triazolin-5-ylidenes, thiazolin-2-ylidenes) and aldehydes is reported. An ammonium charge tag is introduced through the aldehyde unit or the NHC. ESI-MS IR ion spectroscopy allowed the unambiguous conclusion that in the gas phase, the imidazolidin-2-ylidene-derived BI indeed exists as a diamino enol, while both 1,2,4-triazolin-5-ylidenes and thiazolin-2-ylidenes give the keto tautomer. This result coincides with the tautomeric states observed for the BIs in solution (NMR) and in the crystalline state (XRD), and is in line with our earlier calculations on the energetics of BI keto–enol equilibria. 相似文献
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Ewa Odrobina Jianrong Feng Mitchell A. Winnik 《Journal of polymer science. Part A, Polymer chemistry》2000,38(21):3933-3943
The aqueous phase of a poly(butyl methacrylate) (PBMA) latex dispersion contained an oligomeric component that was isolated after sedimentation of the PBMA latex particles. The component contained both water‐soluble PBMA oligomer and some longer chain species that were present as a very fine colloidal dispersion. We describe the isolation and characterization of this component. This component was then added to a purified PBMA latex dispersion from which the aqueous component was previously removed. Latex films were prepared, and in the presence of the oligomeric material, the rate of polymer diffusion in the latex film was strongly enhanced. The magnitude of the enhancement was fit quantitatively to the Fujita–Doolittle equation, indicating that the oligomers acted like a traditional plasticizer to increase the free volume in the system. © 2000 John Wiley & Sons, Inc. J Polym Sci A: Polym Chem 38: 3933–3943, 2000 相似文献
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高效液相色谱荧光测定及质谱鉴定土壤和苔藓中的脂肪酸 总被引:1,自引:0,他引:1
以吖啶酮-9-乙基对甲苯磺酸酯(AETS)作荧光衍生化试剂,建立了灵敏、简单的游离脂肪酸反相高效液相色谱测定方法。在Ec lipse XDB-C8色谱柱上,实现了19种游离脂肪酸(FFA)衍生物的完全基线分离。选取AETS摩尔数为脂肪酸的6倍,以DMF作溶剂,在85℃条件下以K2CO3作催化剂可获得稳定的荧光产物,条件温和、衍生产率高。利用柱后在线串联质谱以APC I大气压化学电离源正离子模式实现了各组分的质谱定性。对土壤和3种苔藓植物中(树藓、狭叶绢藓、曲尾藓)FFA组分定量结果表明,苔藓植物从土壤中富集了大量的游离脂肪酸。荧光检测的激发和发射波长分别为404 nm和440 nm。绝大多数脂肪酸的线性相关系数大于0.9996,检出限为12.3~43.7 fmol。本方法具有良好的重现性,用于实际样品测定,结果满意。 相似文献
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Michaela Fecková Ioannis Konstantinos Kalis Dr. Thierry Roisnel Dr. Pascal le Poul Prof. Oldřich Pytela Dr. Milan Klikar Prof. Françoise Robin-le Guen Prof. Filip Bureš Prof. Mihalis Fakis Dr. Sylvain Achelle 《Chemistry (Weinheim an der Bergstrasse, Germany)》2021,27(3):1145-1159
Six pyrimidine-based push–pull systems substituted at positions C2 and C4/6 with phenylacridan and styryl moieties, employing methoxy or N,N-diphenylamino donors, have been designed and synthesized through cross-coupling and Knoevenagel reactions. X-ray analysis confirmed that the molecular structure featured the acridan moiety arranged perpendicularly to the residual π system. Photophysical studies revealed significant differences between the methoxy and N,N-diphenylamino chromophores. Solvatochromic studies revealed that the methoxy derivatives showed dual emission in polar solvents. Time-resolved spectroscopy revealed that the higher energy band involved very fast (<80 ps) fluorescence, whereas the lower energy one included long components (≈30 ns) due to long-lived intramolecular charge-transfer fluorescence. In contrast to N,N-diphenylamino chromophores, the methoxy derivatives also showed aggregation-induced emission in mixtures of THF/water, as well as dual emission in thin films, covering almost the whole visible spectrum with corresponding chromaticity coordinates not far from that of pure white light. These properties render the methoxy derivatives as very promising organic materials for white organic light-emitting diodes. 相似文献
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Edurne Avellanal-Zaballa Alejandro Prieto-Castañeda Fernando García-Garrido Prof. Antonia R. Agarrabeitia Dr. Esther Rebollar Dr. Jorge Bañuelos Prof. Inmaculada García-Moreno Prof. María J. Ortiz 《Chemistry (Weinheim an der Bergstrasse, Germany)》2020,26(68):16080-16088
The search for long-lived red and NIR fluorescent dyes is challenging and hitherto scarcely reported. Herein, the viability of aza-BODIPY skeleton as a promising system for achieving thermal activated delayed fluorescent (TADF) probes emitting in this target region is demonstrated for the first time. The synthetic versatility of this scaffold allows the design of energy and charge transfer cassettes modulating the stereoelectronic properties of the energy donors, the spacer moieties and the linkage positions. Delayed emission from these architectures is recorded in the red spectral region (695–735 nm) with lifetimes longer than 100 μs in aerated solutions at room temperature. The computational-aided photophysical study under mild and hard irradiation regimes disclose the interplay between molecular structure and photonic performance to develop long-lived fluorescence red emitters through thermally activated reverse intersystem crossing. The efficient and long-lasting NIR emission of the newly synthesized aza-BODIPY systems provides a basis to develop advanced optical materials with exciting and appealing photonic response. 相似文献
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Toby D. M. Bell Dr. Sheryll Yap Chintan H. Jani Sheshanath V. Bhosale Dr. Johan Hofkens Prof. Frans C. De Schryver Prof. Steven J. Langford Prof. Kenneth P. Ghiggino Prof. 《化学:亚洲杂志》2009,4(10):1542-1550
The synthesis and photophysics of two new aminopropenyl naphthalene diimide (SANDI) dyes are reported. A general and convenient method for the synthesis of the precursor mono‐, di‐, and tetrabrominated 1,4,5,8‐naphthalene tetracarboxylic dianhydrides is described. The two core‐substituted SANDIs exhibit many of the photophysical properties required for fluorescence labeling applications including high photostability and high fluorescence quantum yields (>0.5) in the visible region of the spectrum. The emission wavelength is sensitive to the number of substituents on the NDI core, and the fluorescence decay times are in the range of ~8–12 ns for both compounds in the solvents investigated. Preliminary fluorescence emission data from single molecules of the compounds embedded in poly(methyl methacrylate) films are also reported and show that single molecules have very low yields of photobleaching, particularly the di‐substituted system. Furthermore, only a small proportion (<10 %) of the single molecules studied display fluorescence intermittencies or “blinks” in their photon trajectory. The compounds appear to be excellent candidates for applications at the single molecule level, for example, as FRET labels. 相似文献
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Retention of Native Protein Structures in the Absence of Solvent: A Coupled Ion Mobility and Spectroscopic Study 下载免费PDF全文
Dr. Jongcheol Seo Waldemar Hoffmann Dr. Stephan Warnke Prof. Dr. Michael T. Bowers Prof. Dr. Kevin Pagel Dr. Gert von Helden 《Angewandte Chemie (International ed. in English)》2016,55(45):14173-14176
Can the structures of small to medium‐sized proteins be conserved after transfer from the solution phase to the gas phase? A large number of studies have been devoted to this topic, however the answer has not been unambiguously determined to date. A clarification of this problem is important since it would allow very sensitive native mass spectrometry techniques to be used to address problems relevant to structural biology. A combination of ion‐mobility mass spectrometry with infrared spectroscopy was used to investigate the secondary and tertiary structure of proteins carefully transferred from solution to the gas phase. The two proteins investigated are myoglobin and β‐lactoglobulin, which are prototypical examples of helical and β‐sheet proteins, respectively. The results show that for low charge states under gentle conditions, aspects of the native secondary and tertiary structure can be conserved. 相似文献
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Asia Al-jabiry Dr. Martin Palmer Dr. James Langridge Dr. Jeddidiah Bellamy-Carter Dr. David Robinson Prof. Neil J. Oldham 《Chemistry (Weinheim an der Bergstrasse, Germany)》2021,27(55):13783-13792
Native mass spectrometry is now an important tool in structural biology. Thus, the nature of higher protein structure in the vacuum of the mass spectrometer is an area of significant interest. One of the major goals in the study of gas-phase protein structure is to elucidate the stabilising role of interactions at the level of individual amino acid residues. A strategy combining protein chemical modification together with collision induced unfolding (CIU) was developed and employed to probe the structure of compact protein ions produced by native electrospray ionisation. Tractable chemical modification was used to alter the properties of amino acid residues, and ion mobility-mass spectrometry (IM-MS) utilised to monitor the extent of unfolding as a function of modification. From these data the importance of specific intramolecular interactions for the stability of compact gas-phase protein structure can be inferred. Using this approach, and aided by molecular dynamics simulations, an important stabilising interaction between K6 and H68 in the protein ubiquitin was identified, as was a contact between the N-terminus and E22 in a ubiquitin binding protein UBA2. 相似文献
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Christian Steinmetzger Carmen Buerlein Claudia Hbartner 《Angewandte Chemie (International ed. in English)》2020,59(17):6760-6764
RNA aptamers form compact tertiary structures and bind their ligands in specific binding sites. Fluorescence‐based strategies reveal information on structure and dynamics of RNA aptamers. Herein, we report the incorporation of the universal emissive nucleobase analog 4‐cyanoindole into the fluorogenic RNA aptamer Chili, and its application as a donor for supramolecular FRET to the bound ligands DMHBI+ or DMHBO+. The photophysical properties of the new nucleobase–ligand‐FRET pair revealed structural restraints for the overall RNA aptamer organization and identified nucleotide positions suitable for FRET‐based readout of ligand binding. This strategy is generally suitable for binding‐site mapping and may also be applied for responsive aptamer devices. 相似文献
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A cationic water‐soluble conjugated polyelectrolyte, poly[9,9‐bis(6′′‐(N,N,N‐trimethylammonium)hexyl)fluorene‐co‐alt‐2,5‐bis(6′‐(N,N,N‐trimethylammonium)hexyloxyphenylene) tetrabromide], was synthesized. Fluorescence resonant energy transfer (FRET) experiments between the polymer and fluorescein‐labeled single‐stranded DNA (ssDNA‐Fl) were conducted in aqueous buffer and THF/buffer mixtures. Weak fluorescence emission in aqueous buffer was observed upon excitation of the polymer, whereas addition of THF turned on the fluorescence. Fluorescence self‐quenching of ssDNA‐Fl in the ssDNA‐Fl/polymer complexes as well as electron transfer from the polymer to fluorescein may account for the low fluorescence emission in buffer. The improved sensitization of fluorescence by the polymer observed in THF/buffer could be attributed to the weaker binding between the polymer and ssDNA‐Fl and a decrease in dielectric constant of the solvent mixture, which disfavors electron transfer. THF‐assisted signal sensitization was also observed for the polymer and fluorescein‐labeled double‐stranded DNA (dsDNA‐Fl). These results indicate that the use of cosolvent provides a strategy to improve the detection sensitivity for biosensors based on the optical amplification provided by conjugated polymers. 相似文献
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Novel phenylene-bridged zinc bisporphyrins (1-4), fulleropyrrolidines (C60-m, C60-h) and their N-oxides (C60-mo, C60-ho) were synthesized. The fluorescence quenching processes of bisporphyrins in toluene solution by fulleropyrrolidines and their N-oxides were investigated by steady-state fluorescence spectra. The fluorescence quenching constants proved that the fluorescence quenching ability was decreased as reduction of the pyrrolidine functional groups of fullerene surface: C60-h〉C60-m〉C60, and the fluorescence quenching ability was increased about 1.3-7.4 times by utilizing fulleropyrrolidine N-oxides (C60-mo, C60-ho) compared to fulleropyrrolidine compounds (C60-m, C60-h). The results revealed photoinduced electron transfer (PET) efficiency between bispor-phyrin and fullerene derivatives could be tunable by change of functional groups on fullerene surface. 相似文献
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离子交换色谱-氢化物发生双道原子荧光法同时测定砷和硒形态 总被引:4,自引:2,他引:4
建立了离子交换色谱-氢化物发生双道原子荧光联用同时测定4种As形态和3种Se形态的方法,并优化了各种实验参数。采用PRP-X100阴离子交换分析柱可以在10min内同时分离、检测As和Se形态。在8%HCl和1.5%(m/V)KBH4的氢化物反应条件下,进样量100μL,各形态的检出限为:As(Ⅲ)0.2μg/L、DMA0.3μg/L、MMA0.2μg/L、As(Ⅴ)0.3μg/L、SeCys0.6μg/L、Se(Ⅳ)0.5μg/L、SeMet3μg/L。当各As形态浓度为100μg/L、各Se形态浓度为200μg/L,各形态的精密度RSD(n=7)均小于5%。当各As形态浓度范围为5~100μg/L、SeCys和Se(Ⅳ)浓度范围为10~200μg/L、SeMet浓度范围为50~200μg/L时,各形态均可得到良好的线性关系,线性相关系数均大于0.9992。用建立的方法测定了富硒营养品中的As和Se形态,加标回收率在91%~115%之间。 相似文献
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《Chemphyschem》2003,4(8):792-808
This review presents an overview of the fluorescence detection and spectroscopy of single molecules (SMS) in liquids and on surfaces under ambient conditions. The various techniques of SMS, such as confocal epifluorescence detection and wide‐field imaging are presented and discussed, together with the different methods of data analysis such as fluorescence correlation spectroscopy and burst‐by‐burst analysis. Selected applications of the various techniques in physics, chemistry, and biology are described. 相似文献
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利用Yamamoto聚合反应, 通过调节单体2,7-二溴9,9'-二-(三乙氧基甲基)芴和2,7-二溴芴酮的比例, 合成了侧链为极性聚醚链, 芴酮含量逐渐增加的聚芴系列. 通过聚合物溶液及固态薄膜的紫外荧光谱图, 深入研究芴酮作为能量受体的能量转移过程及其对聚合物光物理性质的影响. 结果表明: 稀溶液中体系呈现聚芴本征态的荧光发射, 能量转移对溶液浓度具有依赖性; 固态薄膜中能量转移效率随芴酮含量的增加而快速增长, 退火后这种现象更加明显. 相似文献