Photofragmentation of and electron photodetachment from a GFP model chromophore in a quadrupole ion trap
Photofragmentation of and electron photodetachment from a GFP model chromophore in a quadrupole ion trap
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DOI：
10.1016/j.ijms.2011.08.016
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发表时间：
2011-12-01
影响因子：
1.8
通讯作者：
Jockusch, Rebecca A.
中科院分区：
文献类型：
--
作者：
Forbes, Matthew W.;Nagy, Andrea M.;Jockusch, Rebecca A.
虽然绿色荧光蛋白（GFP）广泛用于生物科学，但控制GFP荧光与非辐射衰变途径的物理学还没有很好地理解。在先前的工作（福布斯和Jockusch，J. Am. Soc.2009），我们报道了GFP的气态阴离子模型发色团，对羟基亚苄基-2，3-二甲基咪唑酮（HBDI-），通过电子光分离（ePD）以及光致断裂而失活。在四极离子阱（QIT）质谱仪中，这两种途径在激活HBDI-后测量到不同的电子作用谱。在这里，我们探索的机制HBDI解离后，在两个特征波长：410 nm，在其中的主要途径是ePD和在480 nm，在其中的分支比之间的ePD和碎片强烈依赖于实验条件。结果表明，从HBDI-在410 nm处的ePD是一个单光子过程，其速率不受改变氦浴气体的压力的影响。这与410 nm处的快速电子脱离过程一致。在480 nm处，QIT中的光致碎裂需要吸收一个以上的光子，并通过碰撞抑制，而ePD由单光子和多光子吸收引起。一个模型，占所有这些意见进行了讨论。ePD和有效吸收截面的估计是碰撞冷却的QIT内的速率。这项工作探讨了吸收和行动光谱之间的联系，适用于生物学上重要的生色团的光物理学。(C)2011 Elsevier B. V.保留所有权利。
Although green fluorescent protein (GFP) is widely used in the biological sciences, the photophysics controlling GFP fluorescence versus non-radiative decay pathways are not well understood. In previous work (Forbes and Jockusch, J. Am. Chem. Soc. 2009), we reported that a gaseous anionic model chromophore of GFP, p-hydroxybenzylidene-2,3-dimethylimidazolone (HBDI-), deactivates via electron photodetachment (ePD) as well as photofragmentation. Distinct electronic action spectra were measured for these two pathways upon activation of HBDI- in a quadrupole ion trap (QIT) mass spectrometer. Here, we explore the mechanisms of HBDI- dissociation following photoexcitation at two characteristic wavelengths: 410 nm, at which the dominant pathway is ePD and at 480 nm, at which the branching ratio between ePD and fragmentation depends strongly on the experimental conditions employed. The results indicate that ePD from HBDI- at 410 nm is a single photon process with a rate that is unaffected by changing the pressure of the helium bath gas. This is consistent with a prompt electron detachment process at 410 nm. At 480 nm, photofragmentation in the QIT requires absorption of more than one photon and is suppressed by collisions, while ePD results from both single and multiple photon absorption. A model that accounts for all these observations is discussed. ePD and effective absorption cross sections are estimated as is the rate of collisional cooling within the QIT. This work explores the connection between absorption and action spectroscopy as applied to the photophysics of a biologically important chromophore. (C) 2011 Elsevier B.V. All rights reserved.