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1.
P. I. H. Bastiaens S. G. Mayhew E. M. O'Naulláin A. van Hoek A. J. W. G. Visser 《Journal of fluorescence》1991,1(2):95-103
Both a mode-locked argon-ion laser and synchrotron radiation were used as excitation sources to obtain time-resolved polarized fluorescence of the two FAD cofactors in electron transferring flavoprotein fromMegasphaera elsdenii. Red-edge excited and blue-edge detected fluorescence anisotropy decay curves did not contain a fast relaxation process which was observed upon mainband excitation and detection. This relaxation was assigned to homo-energy transfer between the two FAD cofactors. Failure of energy transfer as observed with edge spectroscopy on this protein excludes restricted reorientational motion of the flavins as a possible mechanism of depolarization. From the global analysis of the fluorescence anisotropy decay surface obtained at multiple excitation and detection wavelengths, the distance between and the relative orientation of the flavins could be estimated. The methodology described has general applicability in other multichromophoric biopolymers and has the potential to acquire accurate geometrical parameters in these systems. 相似文献
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3.
层状锑磷酸嵌接式卟啉锰制备与模拟细胞色素氧化催化研究 总被引:1,自引:0,他引:1
层状锑磷酸嵌接式卟啉锰制备与模拟细胞色素氧化催化研究胡希明,皮宗新,梅治乾,古国榜,黄仲涛(华南理工大学应用化学系,华南理工大学化学工程系,广州,510641)关键词卟啉锰,层状锑磷酸,嵌接,催化性能细胞色素P450是一种含血红素的单充氧化酶,在室温... 相似文献
4.
N. V. Shcherbatska A. van Hoek P. I. H. Bastiaens A. J. W. G. Visser 《Journal of fluorescence》1995,5(2):171-177
We have studied the fluorescent properties of a well-defined model flavin compound (3-methyllumiflavin) in a relatively polar solvent like propylene glycol or ethanol. Inhomogeneous spectral broadening effects were directly time-resolved by detection at the extreme blue and red edges of the fluorescence band of 3-methyllumiflavin using excitation in the main absorption band. At the high-energy side of the emission band a rapid decay component (tens of picoseconds) was resolved indicative for the disappearance of the initially prepared, nonequilibrium state with a characteristic dipolar relaxation time. At the low-energy side the rise of a solvent relaxed fluorescent species could be time-resolved. The wavelength-dependent effects on the dipolar relaxation were abolished when excitation was at the low-energy side of the absorption band. The experimental decays of the flavin solvate at different energies of fluorescence and excitation are presented as they represent an easy diagnosis for energy dependent solvation dynamics. Wavelength dependent rotation of 3-methyllumiflavin, examined by fluorescence anisotropy decay, turned out to be absent for 3-methyllumiflavin in propylene glycol between 263 and 293 K, probably because of the small change in dipole moment upon flavin excitation. 相似文献
5.
Phytochemical investigation of the bulbs of Fritillaria hupehensis resulted in the isolation and structural elucidation of a new highly conjugated alkaloid of veratramine type identified as 3β,23β-dihydroxy-7,12(14)-dien-5α- veratramin-6-one (1), together with two known alkaloids, ebeinine (2) and zhebeinine (3), which were isolated for the first time from F. hupehensis. The structures of alkaloids 1-3 were established by extensive 1D and 2D NMR spectral analyses. 相似文献
6.
敬钊毒素-I(JZTX-I)是一种能够抑制心肌钠通道失活的新型蜘蛛神经毒素,该文结合高效液相色谱与色氨酸荧光测定技术研究了JZTX-I的磷脂膜结合活性。脂质体共沉淀实验表明,JZTX-I具有不依赖于带负电荷磷脂组成的生物膜结合活性。当加入由酸性或中性磷脂构成的脂质体后,JZTX-I能够分别产生6.4和4.7nm的蓝移以及7.4和8.0nm的红移激发漂移,显示JZTX-I能够插入磷脂膜,同时该分子疏水表面的色氨酸残基处于一个运动受限的界面区域。荧光淬灭实验进一步证实,与脂质体结合能够减少该毒素分子表面色氨酸残基的溶剂暴露。该研究结果为阐明JZTX-I的离子通道门控调节机制提供了新的信息。 相似文献
7.
Introduction Aconitine-type alkaloids isolated from the roots of Aconitum carmiechaeli show a potential toxicity a broad spectrum of bioactivity-. On the basis of the C-substituent of C-diterpenoid skeleton aconitinetype alkaloids can be divided into diester-diterpenoid alkaloids 《高等学校化学研究》2007,23(5):625-627
Introduction Aconitine-type alkaloids isolated from the roots of Aconitum carmiechaeli show a potential toxicity and a broad spectrum of bioactivity[1-4].On the basis of the C8-substituent of C19-diterpenoid skeleton,aconitine-type alkaloids can be divided into diester-diterpenoid alkaloids(DDAs),monoester-diterpenoid alkaloids(MDAs),and lipo-alkaloids(Fig.1). 相似文献
8.
己内酰胺在苯甲酸和6-氨基己酸存在下的聚合反应,实验结果表明苯甲酸具有引发 单体聚合、酸解大分子链和酰化大分子的氨基的作用。反应的开始为催化引发单体生成大分子链而不是苯甲酸与单体的加成。随着大分子的增多,酸解和酰化也同时发生。在反应半小时后酸解的影响逐渐显著,到3—4小时以后,酸解影响超过缩聚使聚合物分子量下降羧基含量增加。到反应7—8小时后,聚合物生成量及分子量已达恒定而酰化仍继续进行。到反应达到平衡时,仍然有游离的苯甲酸,聚合物中仍有游离的氨基和羧基,说明酸解、酰化与缩聚都是可逆反应。 在不用苯甲酸的己内酰胺与水的聚合实验中,聚合物虽在常压通氮的情况下在250°,270°或300°加热6小时分子量仍能稳定在一定数值而不升高,即加热15小时(250°)变化也很小。氨基与羧基不再进行缩聚,可能系由于反应系统粘稠,水分子不易扩散除去,大分子不易移动接触,功能基又受本身分子链的空间阻碍,使反应不易继续进行,维持在一定平衡状态。 相似文献
9.
敬钊毒素-I(JZTX-I)是一种能够抑制心肌钠通道失活的新型蜘蛛神经毒素,该文结合高效液相色谱与色氨酸荧光测定技术研究了JZTX-I的磷脂膜结合活性。脂质体共沉淀实验表明,JZTX-I具有不依赖于带负电荷磷脂组成的生物膜结合活性。当加入由酸性或中性磷脂构成的脂质体后,JZTX-I能够分别产生6.4和4.7 nm的蓝移以及7.4和8.0 nm的红移激发漂移,显示JZTX-I能够插入磷脂膜,同时该分子疏水表面的色氨酸残基处于一个运动受限的界面区域。荧光淬灭实验进一步证实,与脂质体结合能够减少该毒素分子表面色氨酸残基的溶剂暴露。该研究结果为阐明JZTX-I的离子通道门控调节机制提供了新的信息。 相似文献
10.