Lammich L, Petersen M Axman, Nielsen M Brøndsted, Andersen L H
Department of Physics and Astronomy, University of Aarhus, Aarhus, Denmark.
Biophys J. 2007 Jan 1;92(1):201-7. doi: 10.1529/biophysj.106.093674. Epub 2006 Oct 13.
We have studied the gas-phase absorption properties of the green fluorescent protein (GFP) chromophore in its neutral (protonated) charge state in a heavy-ion storage ring. To accomplish this we synthesized a new molecular chromophore with a charged NH(3) group attached to a neutral model chromophore of GFP. The gas-phase absorption cross section of this chromophore molecule as a function of the wavelength is compared to the well-known absorption profile of GFP. The chromophore has a maximum absorption at 415 +/- 5 nm. When corrected for the presence of the charged group attached to the GFP model chromophore, the unperturbed neutral chromophore is predicted to have an absorption maximum at 399 nm in vacuum. This is very close to the corresponding absorption peak of the protein at 397 nm. Together with previous data obtained with an anionic GFP model chromophore, the present data show that the absorption of GFP is primarily determined by intrinsic chromophore properties. In other words, there is strong experimental evidence that, in terms of absorption, the conditions in the hydrophobic interior of this protein are very close to those in vacuum.
我们在重离子储存环中研究了处于中性（质子化）电荷状态的绿色荧光蛋白（GFP）发色团的气相吸收特性。为实现这一目标，我们合成了一种新的分子发色团，其带有一个连接在GFP中性模型发色团上的带电荷的NH(3)基团。将该发色团分子的气相吸收截面作为波长的函数，与GFP的著名吸收光谱进行比较。该发色团在415±5nm处有最大吸收。当校正连接在GFP模型发色团上的带电基团的存在后，预计未受干扰的中性发色团在真空中的最大吸收波长为399nm。这与该蛋白在397nm处的相应吸收峰非常接近。结合之前用阴离子GFP模型发色团获得的数据，目前的数据表明GFP的吸收主要由发色团的固有特性决定。换句话说，有强有力的实验证据表明，就吸收而言，该蛋白疏水内部的条件与真空中的条件非常接近。
