Fluorescence spectra of human neuroglobin

The fluorescence quenching spectra of neuroglobin by cesium ion, iodide and acrylamide, synchronous fluorescence spectra, and 8-anilino-1-naphthalene-sulfonic acid binding property were investigated. The intrinsic fluorescence of neuroglobin cannot be effectively quenched by cesium ion, with a Stern–Volmer constant of 0.23?±?0.01. However, it can be significantly quenched by iodide and acrylamide with Stern–Volmer constants of 1.30?±?0.04 and 4.56?±?0.10, respectively. The results of synchronous fluorescence spectra indicate that tryptophan residues are distributed on both the surface and interior of neuroglobin molecule, but most of them are buried in the hydrophobic interior. The neuroglobin molecule has different conformational states in various pH solutions.     

Study of the Interaction of Fangchinoline with Human Serum Albumin by Fluorescence and UV Spectroscopic Method

The interaction of fangchinoline with human serum albumin (HSA) was studied by use of fluorescence quenching spectra, synchronous fluorescence spectra, and ultraviolet spectra. It was shown that fangchinoline has a strong ability to quench the fluorescence of HSA. The Stern‐Volmer curves based on the quenching of the fluorescence of HSA by fangchinoline indicated that the quenching mechanism of fangchinoline on HSA was static quenching and non‐radiation energy transfer. Based on the Förster theory of non‐radiation energy transfer, the binding distances (r) and the binding constants (K _A) between fangchinoline and HSA were found. The thermodynamic parameters obtained revealed that the interaction between fangchinoline and HSA was mainly driven by hydrophobic force. The conformational changes of HSA were investigated by use of synchronous fluorescence. The result indicates that an ionic electrostatic interaction between fangchinoline and HSA could not be excluded.     

荧光光谱法研究咖啡因与肌红蛋白的相互作用

采用荧光光谱法在生理pH 7.4条件下研究了药物咖啡因与肌红蛋白分子间的相互作用,表明这种相互作用能使肌红蛋白的内源荧光猝灭。通过猝灭常数,结合常数和结合位点数的计算,证明此猝灭为静态猝灭机制。咖啡因和肌红蛋白形成1∶1稳定配合物,形成常数(18 ℃)K_A=1.82×104 L·mol-1;根据热力学参数确定了它们之间的主要作用力为疏水力和静电力。利用同步荧光光谱法研究了咖啡因对肌红蛋白构象的影响。咖啡因能使肌红蛋白的构象发生改变,导致蛋白质分子中色氨酸和酪氨酸残基所处微环境由原来的疏水环境不同程度地向亲水环境转变。     

双酰胺稀土配合物的合成及荧光性能

为寻求发光性能良好的配合物,设计合成了一种新的双酰胺配体1,4-二 苯(L),并在氯仿和乙酸乙酯溶液中合成了其与硝酸钐、硝酸铕和硝酸铽的发光稀土配合物。元素分析数据表明稀土硝酸盐与配体形成的是 1 : 1 型的配合物;红外光谱显示配合物具有相似的配位结构。对配体及其配合物的荧光进行了详细的研究,结果表明:钐、铕和铽配合物分别呈现出Sm³⁺、Eu³⁺、Tb³⁺的特征发射,铕离子处于不对称中心格位,硝酸铽配合物荧光相对强度最大。     

Structure and Anti-Tumor Activity of Bovine alpha-Lactalbumin after Binding Linoleic AcidSCIEI北大核心CSCD

The structure changes of alpha-lactalbumin after binding oleic acid and linoleic acid, including hydrophobic amino acids, hydrophobic regions, tertiary structure, secondary structure, was studied by intrinsic fluorescence, ANS-binding intrinsic fluorescence and circular dichroism spectrum, respectively. The anti-tumor activity of the lactalbumin-oleic acid complex and lactalbumin-linoleic acid complex was measured using the methylene blue method. It can be seen from the fluorescence spectra that a significant red-shift from 331.07 to 337.67 nm and 337.60 nm of alpha-lactalbumin occurred after binding of oleic acid and linoleic acid, respectively. Together with the ANS-binding spectra, which exhibited a blue-shift (from 516.20 to 514.10 nm and 508.50 nm, respectively) with an increased fluorescence intensity, it can be indicated that binding of oleic acid and linoleic acid lead to the exposure of hydrophobic amino acids and hydrophobic regions. Results of circular dichroism spectra indicated the partial loss of the tertiary structure, and an decrease of beta-turn and random coil, which turn to the p-sheet structure. Furthermore, the antitumor activity of the two complexes was verified on the three types of tumor cells. This study laid a theoretical basis for the development of anti-tumor drugs.     

牛α-乳白蛋白-亚油酸复合物的结构及抗肿瘤活性

利用内源性荧光光谱、荧光探针(ANS)结合荧光光谱及圆二色谱,以乳白蛋白-油酸为参照,研究了乳白蛋白结合亚油酸后,疏水性氨基酸、疏水性区域、三级结构及二级结构的变化,并利用亚甲基蓝的方法评价了该复合物的抗肿瘤活性。荧光光谱结果显示,与乳白蛋白-油酸复合物类似,乳白蛋白结合亚油酸后,其内源性荧光光谱显著红移,从331.07 nm移至337.60 nm;外源性ANS结合光谱蓝移,从516.20 nm移至508.50 nm;且荧光强度增加,表明乳白蛋白结合亚油酸后同样出现了疏水性氨基酸及疏水性区域暴露的现象。圆二色谱结果表明,与乳白蛋白-油酸复合物类似,乳白蛋白结合亚油酸后,三级结构部分丧失,二级结构中β-转角及无规卷曲的含量显著降低,β-折叠含量增加。细胞实验证实了乳白蛋白-亚油酸复合物具有良好的抗肿瘤效果。该研究从复合物结构和功能的两方面,为新型抗肿瘤乳白蛋白-亚油酸复合物的开发提供了依据。     

芬布芬与牛血清白蛋白相互作用的荧光光谱检测

在模拟生理条件下,用荧光光谱法和紫外-可见吸收光谱法研究芬布芬(FBF)和牛血清白蛋白(BSA)结合反应的特征.研究表明:芬布芬与牛血清白蛋白形成复合物,从而猝灭牛血清白蛋白的内源性荧光,该过程为静态猝灭过程.根据Stem-V(o)lmer方程得出了不同温度下结合位点数和结合常数;根据F(0)rster非辐射能量转移理...     

S-构型转化对卵白蛋白微观结构的影响

采用圆二色谱(CD)、X射线衍射(XRD)、ANS荧光探针和紫外光谱(UV)研究了S-构型转化对卵白蛋白微观结构的影响.结果显示,不同诱导时间处理的卵白蛋白二级结构的α-螺旋,β-折叠,β-转角和无规卷曲之间相互转化,α-螺旋略有减少,β-折叠相应增加,分子有序性提高;S-构型转化后卵白蛋白晶体结构增加,72 h处理后...     

防己诺林碱与牛血清白蛋白相互作用的研究

在不同温度下,用荧光猝灭光谱、同步荧光光谱和紫外-可见吸收光谱,研究了防己诺林碱与BSA相互作用的光谱学行为。防己诺林碱对BSA有较强的荧光猝灭作用。根据不同温度下防己诺林碱对BSA的荧光猝灭作用,利用Stern-Volmer方程处理实验数据,表明防己诺林碱对BSA的荧光猝灭作用属于静态猝灭。根据Frster非辐射能量转移理论计算出了防己诺林碱与BSA间的结合距离R(27 ℃ 2.51 nm; 37 ℃ 2.72 nm; 47℃ 2.89 nm)、结合常数K_A(27 ℃ 1.05×105 L·mol-1; 37 ℃ 3.31×105 L·mol-1; 47 ℃ 7.24×105 L·mol-1)及对应温度下的热力学参数。热力学数据表明二者主要靠疏水作用力结合,同时用同步荧光光谱探讨了防己诺林碱对BSA构象的影响。     

Interaction of transferrin with cefuroxime sodium

ABSTRACT

The interaction between cefuroxime sodium and transferrin in physiological buffer (pH 7.4) was investigated by spectroscopy at 298, 310, and 318?K. The analysis of data indicated that quenching mechanism of the transferrin–cefuroxime sodium system was probably static. The electrostatic force played an important role in the conjugation reaction between transferrin and cefuroxime sodium. The order of magnitude of binding constants (K_a) was 10⁴, and the number of binding site (n) in the binary system was approximately equal to 1. Besides, the values of Hill’s coefficients were lager than 1, which indicated very weakly positive cooperativity in the transferrin–cefuroxime sodium system. The synchronous fluorescence spectra and circular dichroism spectra revealed that the microenvironment and the conformation of transferrin were changed during the binding reaction.     

动态超高压微射流对卵清蛋白微观结构的影响

采用圆二色谱(CD)、X射线衍射(XRD)、ANS荧光探针和紫外(UV)光谱研究了动态超高压微射流对卵清蛋白微观结构的影响。结果表明：卵清蛋白的微观结构的变化与处理压力有关,CD显示不同压力处理的卵清蛋白二级结构中的α-螺旋,β-折叠,β-转角和无规卷曲之间发生相互转化,二级结构的有序性提高;X射线衍射图谱直观显示不同压力处理的卵清蛋白晶体结构增加,160 MPa处理下结晶区最大,说明蛋白结构的有序性提高,与CD分析结果相似;ANS荧光探针光谱显示卵清蛋白的表面疏水性随着处理压力的增大而提高,120 MPa处理下达到最大;紫外光谱显示随着处理压力的增大,卵清蛋白最大紫外吸光值下降,卵清蛋白分子表面的具有紫外吸收的芳香氨基酸残基被包埋于分子内部,卵清蛋白的三维结构发生改变。     

荧光光谱法研究黄豆黄素与牛血清白蛋白的相互作用

用荧光光谱法在pH 7.4的PBS中研究了黄豆黄素(Glycitein,GL)与牛血清白蛋白(Bovine serum albumin,BSA)分子之间的相互作用方式及机理.结果表明GL可静态猝灭BSA的内源荧光.310K和315K的结合位点数与表观结合常数分别为1.30,8.09×104L·mol-1和1.73,5....     

光谱法研究稀土离子钇(Ⅲ)与牛血清白蛋白的相互作用

用荧光光谱和紫外-可见吸收光谱研究了稀土金属离子Y3+与牛血清白蛋白(BSA)的相互作用。实验结果发现:Y3+对BSA的紫外吸收光谱具有增强作用,而对荧光光谱具有较强的荧光猝灭作用且峰位明显蓝移20～25 nm。用Stern-Volmer方程分别对实验数据进行分析,得出结论:Y3+对BSA的荧光猝灭作用是属于静态荧光猝灭,Y3+与BSA反应生成了新的复合物,发生了分子内的非辐射能量转移。求得相互作用过程的结合常数(KA)和热力学参数(ΔΗ、ΔS、ΔG),确定了它们之间的主要作用力是范德华力、氢键等,但静电作用力也不可忽略。同步荧光光谱法表明Y3+对牛血清白蛋白的构象有影响。     

激光诱导时间分辨固体表面荧光光谱系统

采用斜射式激发样品光路结构,设计了应用于测试时间分辨固体表面荧光光谱系统。利用该系统研究了氧化锌薄膜在355 nm激光脉冲激发下的时间分辨固体表面荧光光谱。结果表明,该系统能够实现测量时间分辨固体表面荧光光谱,并由此测量了样品的固体表面荧光寿命。该系统结构简单可靠,灵敏度高,响应速度快。     

KCl对含有纳米银的[Ru(bpy)3]2+荧光性能影响

通过吸收光谱、荧光光谱等手段研究了KCl对含有纳米银的金属钌联吡啶配合物([Ru(bpy)3]2 )的荧光性能的影响.结果表明,KCl与纳米银粒子间存在较强的相互作用,这种强的相互作用破坏了[Ru(bpy)3]2 与纳米银粒子间的链状网络结构,形成大颗粒和团聚体.同时,在吸收光谱的长波段处观察到明显的新的吸收带,随着KCl量的增加,新吸收带峰值逐渐红移并展宽.随着KCl量的增加,[Ru(bpy)3]2 荧光强度先猝灭而后逐渐增强,直至达到一个定值.文章从分子间的相互作用、能量传递等方面探讨了KCl对含有纳米银的[Ru(bpy)3]2 荧光性能影响机理.     

基于延迟荧光光谱F685/F730温度响应曲线的植物耐热性评价

以3种不同耐热型玉米植株叶片为样品,分析了在10~50 ℃温度胁迫下,样品离体叶片延迟荧光光谱的变化。实验发现:温度对延迟荧光光谱主峰685 nm的最高峰值强度(F₆₈₅)和次峰730 nm的最高峰值强度(F₇₃₀)的比值F₆₈₅/F₇₃₀产生了显著的影响。此外,不同耐热型样品在10 ℃胁迫下的F₆₈₅/F₇₃₀值(V₁₀)与50 ℃胁迫下的F₆₈₅/F₇₃₀值(V₅₀)之间存在显著差异:不耐热样品叶片的V₁₀/V₅₀高于耐热的,越耐热的样品V₁₀/V₅₀值越小,且随着胁迫时间的延长,V₁₀/V₅₀也逐渐减小。因此,通过对实验结果的分析认为,延迟荧光光谱F₆₈₅/F₇₃₀比值是随着温度胁迫规律变化的,F₆₈₅/F₇₃₀比值的温度响应曲线有望成为一种鉴定和评价植物耐热性的新方法。     

胆红素与血红蛋白分子作用的发光光谱分析

利用荧光光谱技术研究了胆红素对血红蛋白分子中发光基团结构变化的影响及其与血红蛋白结合方式。结果表明,不同浓度的胆红素可以不同程度地猝灭血红蛋白荧光,导致330nm处色氨酸残基荧光峰下降,410nm处荧光峰消失;pH值94时血红蛋白与胆红素以非静电引力如疏水作用、范德华力的协同作用结合,且随着作用时间的延长,荧光强度下降。血红蛋白中氨基酸残基上的-NH₂与胆红素分子中两个-COOH结合,形成复杂的卷曲结构。血红蛋白的紫外光谱受胆红素分子中二吡咯发色团的影响,导致光吸收劈裂,在350,406nm处形成肩峰。另外,体系受温度影响也较大。     

Fluorescence Investigation on the Interaction of a Prevalent Competitive Fluorescent Probe with Entomic Odorant Binding Protein

In recent years, one prevalent competitive fluorescent probe, N-phenyl-1-naphthylamine (1-NPN), was frequently utilized to measure the binding affinity of entomic odorant binding proteins (OBPs) with diverse plant volatiles or pheromones. Nevertheless, the details and model of the binding interaction are still largely unknown, although it is vital to investigate the physiological function of OBPs. Here we studied the binding interaction between 1-NPN and OBP2, a recombinant OBP from eastern honeybee, Apis cerana, by the combination of fluorescence quenching spectra, synchronous fluorescence spectra, ultraviolet spectra, circular dichroism spectra, and molecular docking. The Stern–Volmer curve of the fluorescence quenching of OBP2 by 1-NPN indicated it was a static quenching mechanism, and the binding constants and binding number were determined, respectively. Based on the Förster theory of nonradiation energy transfer (FRET), the binding distance was calculated, and the intrinsic fluorescent energy was predicted to transfer from the donor OBP2 to the acceptor 1-NPN. Synchronous fluorescence spectra and circular dichroism spectra were used to investigate the conformational change in binding progress. The thermodynamic parameters showed that the interaction was mainly driven by hydrophobic force, which was validated by the molecular docking; meanwhile, the binding mode was revealed and one hydrogen bond was found between the nitrogen atom of 1-NPN and Glu29 of OBP2.     

热处理对蛋清卵类粘蛋白过敏原性及构象的影响

采用酶联免疫吸附法(ELISA)、圆二色谱(CD)、ANS荧光探针和紫外光谱(UV)系统研究了热处理对蛋清卵类粘蛋白过敏原性及构象的影响。结果显示,加热处理卵类粘蛋白的过敏原性降低,且随加热温度升高和加热时间延长,不断降低。经不同温度热处理后的卵类粘蛋白二级结构的α-螺旋,β-折叠,β-转角和无规卷曲之间相互转化,分子有序性降低;卵类粘蛋白的表面疏水性随加热温度的升高而降低;随加热的温度的升高,具有紫外吸收的氨基酸残基逐渐暴露,最大吸光度逐渐增大。由此可以推断,卵类粘蛋白的构象改变导致其过敏原性变化。     

The human brain hexacoordinated neuroglobin three-dimensional structure

Neuroglobin, mainly expressed in vertebrate brain and retina, is a recently identified member of the globin superfamily. Augmenting O2 supply, neuroglobin promotes survival of neurons upon hypoxic injury, potentially limiting brain damage. In the absence of exogenous ligands, neuroglobin displays a six-coordinated heme. O2 and CO bind to the heme-iron, displacing the endogenous HisE7 heme distal ligand. Hexacoordinated human neuroglobin displays a classical globin fold, adapted to host the reversible bis-histidyl heme complex, and an elongated protein matrix cavity, held to facilitate O2 diffusion to the heme. The structure of neuroglobin suggests that the classical globin fold is endowed with striking adaptability, indicating that hemoglobin and myoglobin are just two examples within a wide and functionally diversified protein homology superfamily.