芳香叔胺引发丙烯酰胺光聚合动力学及机理研究

研究了N,N-二甲基对甲苯胺(DMT)为引发剂时丙烯酰胺(AM)的光聚合。聚合速率与AM、DMT浓度的关系为: R_p∞[DMT]~(0.35)[AM]~(1.34)(水为溶剂) R_p∞[DMT]~(0.33)[AM]~(1.32)(二甲亚砜为溶剂)二甲亚砜为溶剂时,光聚合表观活化能为4.62千卡/克分子。 从光照下DMT与AM形成激发态电荷转移复合物的机制初步讨论了引发机理。     

DISTANCE-DEPENDENT FLUORESCENCE QUENCHING OF TRYPTOPHAN BY ACRYLAMIDE

Abstract We used GHz frequency-domain fluorometry to investigate the time-dependent intensity decays of N -acetyl -L-trytophanamide (NATA) when collisionally quenched by acrylamide in propylene glycol at 20°C. The intensity decays of NATA became increasingly heterogeneous in the presence of acrylamide. The NATA intensity decays were not consistent with the Collins-Kimball radiation boundary condition (RBC) model for quenching. The steady-state Stern-Volmer plots show significant upward curvature. At low temperature in vitrified propylene glycol (-60%), where translational diffusion cannot occur during the lifetime of the excited state, quenching of NATA by acrylamide was observed. The Smoluchowski and RBC quenching models do not predict any quenching in the absence of translational diffusion. Hence, these frequency-domain and steady-state data indicate a through-space quenching interaction between NATA and acrylamide. The rate for quenching of NAT A by acrylamide appears to depend exponentially on the fluorophore-quencher separation distance. Comparison of the time-resolved and steady-state data provides a sensitive method to determine the distance dependence of the fluorophore-quencher interaction. The distance-dependent rate of quenching also explains the upward curvature of the Stern-Volmer plot, which is often observed for quenching by acrylamide. These results suggest that the distance-dependent quenching rates need to be considered in the interpretation of quenching data of proteins by acrylamide.     

RAPID EQUILIBRATION OF OXYGEN IN FLUORESCENCE QUENCHING REACTIONS

A simple means is described for the rapid equilibration of oxygen in fluorescence quenching reactions. This involves bubbling the gas through experimental solutions. With this procedure, data for Stern-Volmer plots can be obtained in 1–2 h, without bubbling it takes approximately ten times as long to collect such data.     

A COMPARISON OF FLUORESCENCE QUENCHING AND FLUORESCENCE DECAY STUDIES WITH TRYPTOPHAN

Abstract— The quenching of the fluorescence of aqueous tryptophan solutions has been studied as a function of emission wavelength using acrylamide as a collisional quencher. Our quenching studies are consistent with recent observations of the heterogeneity of tryptophan fluorescence, but they show a slight discrepancy when compared to certain analyses of the decay of tryptophan fluorescence in terms of two components.     

磺化竹红菌素对蛋白质荧光猝灭机理的研究

本文详细研究了磺化竹红菌素对多种蛋白质在溶液状态下的荧光猝灭过程。结果表明,磺化竹红菌素对多种蛋白质荧光猝灭服从Stern-Volmer曲线,实验观察了温度、粘度、pH值和盐酸胍对荧光猝灭过程的影响。由于磺化竹红菌素是一两性分子,对于不同蛋白具有不同猝灭过程;磺化竹红菌素对蛋白质的荧光猝灭常数K_q在10¹³mol/L·s^-1左右,这说明,磺化竹红菌素是一种比其它蛋白质荧光猝灭剂更加有效的荧光猝灭剂。     

竞争吸收在含金属稳定剂的猝灭机理中的作用

<正> 含重金属原子的光稳定剂的稳定效果常和其光猝灭能力相联系。钱钦文等指出,Ni、Cr、Yb及Eu的整合物能猝灭二乙酮的三重态。Briggs等发现,镍的一系列不同配位体的螯合物可以强烈的猝灭蒽的三重态。有些报告还指出,许多不同配位体的金属螯合物是二苯酮激发态的最佳猝灭剂。但也存在一些相反的结果,如Carlsson等未观     

芦丁对罗丹明6G的荧光猝灭机理研究及其含量测定

根据Stem - Volmer方程和罗丹明6G吸收光谱的变化研究了芦丁对其荧光猝灭的类型及机理,结果表明,芦丁与罗丹明6G作用,形成一种稳定的复合物,而发生荧光静态猝灭,求得复合物的结合常数K=5.55×105L/mol,结合点数n=1.26.芦丁含量在0.92～137.8μg/mL范围内与F0/F成正比,检出限为0....     

ON THE MECHANISM OF FLUORESCENCE QUENCHING IN PYRENE- AND 3,4-BENZOPYRENE-1,3,7,9-TETRAMETHYLURIC ACID SYSTEMS

T he interaction between aromatic hydrocarbons and purine or its analogues has been widely noted in connection with the possibility of complex formation between carcinogens and DNA or its precursors. Weil-Malherbe[1], Boyland and Green[2] reported that 1,3,7,9-tetramethyluric acid (TMUA) solubilizes aromatic hydrocarbons in aqueous solution and exerts a strong quenching action on fluorescence of the hydrocarbons. The solubilization has been attributed to formation of a molecular complex [2]. Complex formation is now thought to be mainly due to van der Waal's force (polarization and dispersion force) rather than charge transfer ( CT ) one[2,3–5]. Van Duuren [3,5] examined fluorescence spectra of TMUA-hydrocarbon complexes both in solution and in potassium bromide pellets. In solution, the fluorescence spectrum of the complex showed no change in the position of the maximum and in intensity, when compared with that of the free hydrocarbon. In the solid state, however, a blue shift was observed for the fluorescence of the complex. From these results, it was concluded that the complex is entirely dissociated in solution and the fluorescence shift observed in the solid state is the result of the interaction in the excited state. The present note describes a new observation which is useful for understanding the mechanism of fluorescence quenching in the hydrocarbons-TMUA systems.     

QUENCHING OF THE FLUORESCENCE OF 8-METHOXYPSORALEN BY PROTONS

Abstract— The quenching of 8-methoxypsoralen (8-MOP) fluorescence by protons was observed to occur at the diffusion controlled rates in aqueous solutions at room temperature. Enhanced basicity of 8-MOP in the excited state compared to the ground state is expected on theoretical grounds. The fluorescence yield. which we determined as 6.3 × 10^--⁴ at pH 1 is surprisingly low and indicative of extremely fast radiationless decay pathways. The fluorescence lifetime of 8-MOP in neutral aqueous solution is on the order of 1–2 ns.     

脱落酸对伊文思蓝的荧光猝灭机理研究及其含量测定

利用荧光光谱研究了脱落酸(Abscisic acid)与伊文思蓝(Evans blue)的相互作用。用266 nm激发光激发时,伊文思蓝的最大发射波长为396 nm。伊文思蓝与脱落酸相互作用,使伊文思蓝发生荧光猝灭,根据Stern-Volmer方程研究了荧光猝灭的类型及机理,实验证明脱落酸与伊文思蓝发生的静态猝灭,即脱落酸和伊文思蓝形成了一种稳定的复合物。伊文思蓝的相对荧光强度与脱落酸的浓度线性相关,线性方程为F0/F=0.78153+3.9153×104c,线性相关系数为0.9976。通过实验求算了脱落酸与伊文思蓝的结合点常数KABA-EB=1.838×105L/mol和结合点数n=1.171,由此建立了测定植物中脱落酸的新方法。     

THE TRANSVERSE LOCATION OF FLUOROPHORES IN LIPID BILAYERS AND MICELLES AS DETERMINED BY FLUORESCENCE QUENCHING TECHNIQUES

Abstract— A fluorescence quenching technique has been used to determine the absolute partition coefficients of a set of n -doxyl stearates which partition between the aqueous and lipid phases of a phospholipid dispersion, and it is shown that the values of the coefficients vary in a systematic way depending on the position of the doxyl group on the acyl chain of the fatty acid. The n -doxyl stearates quench the fluorescence of n -(9-anthroyloxy) fatty acids in lipid bilayers, and consideration of the absolute partition coefficients of the quencher and of the microviscosity of the bilayer is necessary to extract information about the proximity of the fluorophore and quencher. In addition, quenching of the fluorescent fatty acids with a quencher which is small relative to the width of the lipid bilayer allows determination of both the absolute and local partition coefficients, the latter referring to a subvolume of the bilayer within which quenching occurs. The relationship between absolute and local partition coefficients is defined for micelles and bilayers and a method for determining the relative transverse positions of the anthroyloxy rings in these structures is described.     

硝基苯衍生物结构与其淬灭聚(2,5-二戊氧基对亚苯基亚乙炔基)荧光效率的关系

聚对亚苯基亚乙炔基(polyphenyleneethynylenes,PPEs)、聚噻吩(PTs)等作为具有共轭结构的电荷给体,在与含硝基、氰基等电荷受体发生电荷转移络合作用时,其荧光强度会随电荷受体结构的不同而产生不同程度的淬灭,而且响应灵敏度明显高于一般荧光小分子化合物[1~4].这是因为荧光小     

吖啶橙(AO)-藏红T(ST)荧光探针测定DNA的研究

简述了以荧光能量转移本系测定ＤＮＡ方法的发展过程，同时对吖啶（ＡＯ）－藏红Ｔ（ＳＴ）荧光探针测定ＤＮＡ的条件进行分析，证明了该法灵敏度高、线性范围宽、检出限低、选择性好、抗干扰能力强，该法为微曦ＤＮＡ测定分析工作提供了一个新的途径。     

TRYPTOPHANYL FLUORESCENCE QUENCHING OF UROCANASE FROM Pseudomonas putida BY ACRYLAMIDE, CESIUM, IODIDE, and IMIDAZOLEPROPIONATE

Abstract— Urocanase from Pseudomonas putida can be photoactivated by UV radiation. Because of the action spectrum peak at 280 nm, tryptophan has been implicated in the photoactivation by energy transfer. In these studies, tryptophan was determined, the exposure and environment of tryptophanyl residues were studied with collisional quenchers, and the involvement of tryptophanyl residues in the photoactivation of urocanase was investigated. There are sixteen tryptophanyl residues per urocanase molecule as measured by two methods. Fluorescence quenching with acrylamide, cesium, and iodide was used to describe the accessibility and environment of urocanase tryptophanyl residues. Quenching constants indicated there is little difference in the accessibility of tryptophanyl residues between active and inactive enzyme. Tryptophanyl residues of native enzyme were most accessible to acrylamide ( f _a, = 0.6–0.7), less accessible to iodide ( f _a= 0.4), and not accessible to cesium ion, suggesting that surface residues were in regions of positive charge. Stern-Volmer plots indicated a heterogeneous population of tryptophanyl residues with different accessibilities. A competitive inhibitor, imidazolepropionate, quenched fluorescence; the quenching was used to determine the dissociation constant for the enzyme-inhibitor complex ( K _d= 0.20 mM). Kinetic data showed K _i= 0.25 mM. Mixed quencher experiments indicated that the tryptophanyl residues quenched by imidazolepropionate were more accessible to acrylamide and less accessible to iodide. These studies suggest that the residues involved in putative energy transfer during photoactivation are not fully exposed.     

卤素离子对联有吖啶基三元共聚物薄膜的荧光猝灭

在合成了几种带不同组成比吖啶基三元共聚物的基础上,对其溶液和薄膜的吸收与荧光发光光谱进行了表征.研究了上述薄膜在含有卤素阴离子溶液中的荧光猝灭问题,发现含有不同吖啶组成比的薄膜对不同卤素离子具有不同的选择性,过多或过少吖啶含量的薄膜均对选择性的识别卤素阴离子不利,只有在某种特定组成条件下方能得到最佳、具有特征识别阴离子能力的薄膜器件.对所得结果进行了详细的讨论.     

磷钨酸催化合成尿囊素的研究

磷钨酸催化合成尿囊素的研究王为清＊＊辛艳凤文衍宣＊（哈尔滨工程大学化工系，哈尔滨，１５０００１键词磷钨杂多酸尿囊素合成尿囊素是一类重要的医药、日用品的原料［１］。具有促进上皮细胞的形成，使伤口快速愈合的生理功能。对农作物有固果、催熟增产作用，是常用的...     

DETERMINATION OF THE ACRYLAMIDE QUENCHING CONSTANT FOR PROTEIN AND MODEL INDOLE TRIPLETS

Abstract— The decay of the indole triplet of single tryptophan-containing proteins and model compounds can be readily measured at room temperature in aqueous solution by monitoring the triplet-triplet absorption or phosphorescence emission following a 265 nm exciting laser pulse. The quenching action of acrylamide on the triplet excited state of indole side chains was studied in an analogous fashion to that previously done at the singlet level (Eftink and Ghiron, 1977). The acrylamide triplet quenching constant (^tk_q) ranged from a high of 7.8 times 10⁸M^-1 s^-1 for the exterior indole of corticotropin (ACTH) to a low of 2 times 10⁵ Af^-1 s^-1 for the interior indole of ribonuclease T, (RNase T,). The ratio (7) of these values with their respective acrylamide singlet quenching constants (^tk_q),(γ=^tk_q⁸K_q) ranged from a high of 0.22 for ACTH to a low of 0.001 for RNase T₁,. Acrylamide is also an inefficient quencher of model indoles in various solvents (i.e. it has a γ less than 1). The magnitude of γ varied from a high of 0.3 in H₂0 to a low of 0.02 in acetonitrile, but did not correlate with viscosity, dielectric constant or polarity. The lower efficiency observed for internal indole groups can not be explained by that class of models which predict the presence of static quenching at the triplet level, since none was observed. The present results confirm the observation of Calhoun et al. of a large discrepancy between acrylamide's singlet and triplet quenching constants for buried indole side chains, but suggest that it may be largely explained by the fact that acrylamide is an inefficient quencher of the indole triplet state (1983). The magnitude of this inefficiency is probably determined by specific microenvironmental factors. Thus, unlike ⁸K_q, the environmentally sensitive ^lk_H cannot be easily used to characterize the dynamics of proteins.     

ACRYLAMIDE AND MOLECULAR OXYGEN FLUORESCENCE QUENCHING AS A PROBE OF SOLVENT-ACCESSIBILITY OF AROMATIC FLUOROPHORES COMPLEXED WITH DNA IN RELATION TO THEIR CONFORMATIONS: CORONENE-DNA AND OTHER COMPLEXES

Abstract— The relationships between the accessibilities to fluorescence quenchers (O2 and acrylamide) of three different aromatic molecules and their modes of binding to double-stranded DNA were investigated. Proflavin was selected for this study because it is a known intercalator, while Hoechst 33258 is known to bind externally in the minor groove of DNA; it is shown here that the relatively bulky polycyclic aromatic hydrocarbon coronene forms partial intercalation complexes, and thus represents a third class of fluorophore-DNA binding. Fluorescence quenching results suggest that Hoechst 33258 bound to DNA is fully accessible to 02, that the accessibility of partially intercalated coronene is reduced to 20% of the free-solution value, while the accessibility of intercalated proflavin to molecular oxygen is at least ten times smaller than for free polycyclic aromatic molecules in fluid solutions. In contrast, the fluorescence of all these three fluorophores bound to DNA is insensitive to acrylamide (the effective accessibilities appear to be reduced by factors greater than 50 upon binding to DNA). It is concluded that O, is useful as a qualitative probe of the type of binding and solvent exposure of fluorophore-DNA complexes, while acrylamide appears to be of limited utility. However, acrylamide fluorescence quenching may be useful for studies of other types of fluorophore-DNA complexes since the fluorescence of the pyrene residues in covalent adducts derived from the binding of benzo(a)pyrene diol expoxide to DNA was found to be at least partially sensitive to acrylamide.     

THE MECHANISM OF ENERGY TRANSFER FROM POLY-p-BENZOYLPHENYLACETIMIDO-BOVINE SERUM ALBUMIN TO SMALL-MOLECULE QUENCHERS

Abstract— Results of a quantitative photochemical study of poly- p -benzoylphenylacetimido-bovine serum albumin in the presence of small-molecule triplet quenchers are reported. The efficiency of quenching by organic salts containing low triplet energy chromophores is shown to be qualitatively dependent on their predicted association constants to the modified protein. In addition, quenching is inhibited by salts of organic acids which possess high binding affinities for the protein but do not contain chromophores of low triplet energy. Quantitative treatment of the quenching and inhibition data yields results which strongly support the operation of an 'affinity controlled' mechanism for triplet energy transfer from the benzophenone moieties of the modified-bovine serum albumin to quenchers such as α-naphthylacetate and trans -cinnamate.