Department of Physics, Montana State University, Bozeman, MT 59717, USA.
Sci Rep. 2012;2:688. doi: 10.1038/srep00688. Epub 2012 Sep 24.
Rapid photobleaching of fluorescent proteins can limit their use in imaging applications. The underlying kinetics is multi-exponential and strongly depends on the local chromophore environment. The first, reversible, step may be attributed to a rotation around one of the two exocyclic C-C bonds bridging phenol and imidazolinone groups in the chromophore. However it is not clear how the protein environment controls this motion - either by steric hindrances or by modulating the electronic structure of the chromophore through electrostatic interactions. Here we study the first step of the photobleaching kinetics in 13 red fluorescent proteins (RFPs) with different chromophore environment and show that the associated rate strongly correlates with the bond length alternation (BLA) of the two bridge bonds. The sign of the BLA appears to determine which rotation is activated. Our results present experimental evidence for the dominance of electronic effects in the conformational dynamics of the RFP chromophore.
荧光蛋白的快速光漂白会限制它们在成像应用中的使用。其潜在动力学是多指数的，并强烈依赖于局部发色团环境。第一个可逆步骤可能归因于围绕连接发色团中苯酚和咪唑啉酮基团的两个外环己 C-C 键之一的旋转。然而，目前尚不清楚蛋白质环境如何控制这种运动——是通过空间位阻还是通过静电相互作用调节发色团的电子结构。在这里，我们研究了 13 种具有不同发色团环境的红色荧光蛋白 (RFP) 中光漂白动力学的第一步，并表明相关速率与两个桥键的键长交替 (BLA) 强烈相关。BLA 的符号似乎决定了哪个旋转被激活。我们的结果为 RFP 发色团构象动力学中电子效应的主导地位提供了实验证据。
