FOURIER-TRANSFORM RESONANCE RAMAN-SPECTROSCOPY OF INTERMEDIATES OF THE PHYTOCHROME PHOTOCYCLE
FOURIER-TRANSFORM RESONANCE RAMAN-SPECTROSCOPY OF INTERMEDIATES OF THE PHYTOCHROME PHOTOCYCLE
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DOI：
10.1021/bi00033a023
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发表时间：
1995-08-22
期刊：
影响因子：
2.9
通讯作者：
SCHAFFNER, K
中科院分区：
文献类型：
--
作者：
MATYSIK, J;HILDEBRANDT, P;SCHAFFNER, K
用低温傅里叶变换共振拉曼光谱研究了124 kDa光敏色素（来自燕麦的phy A）的母体态及其光循环中间产物：首次获得了初级光产物I-700和lumi-F以及热中间产物meta-F的光谱。稳定的光致变色形式的光致变色，P-R和P-FR，在这项工作中提出的光谱是显着更好的信噪比和分辨率比以前公布的光谱，证明了我们的实验方法的独特优势。高光谱质量允许识别振动带图案的细微细节，使得已经从H2O和D2O中的样品测量的共振拉曼光谱构成了用于光敏色素的各种形式的结构分析的坚实基础。尽管目前许多共振拉曼谱带的振动归属存在不确定性，但四吡咯发色团的光谱变化可以合理地用两个不同次甲基桥处的构象变化来解释，即，围绕两个单键的扭转和双键的E/Z异构化。在基于胆绿素二甲酯的振动分析的这种解释的框架内（Smit，K.，Matysik，J.，Hildebrandt，P.，和Mark，F.（1993）J.Phys.Chem.97，11887 - 11900），提出了一种一致的模型来描述光循环期间发色团中的分子事件。可以安全地排除在P的初级光过程中涉及质子转移。然而，以前的结论，发色团质子化的个别国家出现在目前的振动分配状态过早。特别地，在1100（-1）cm处的宽带归因于质子化吡咯啉氮的N-H面外弯曲（Hildebrandt，P.，霍夫曼，A.，Lindemann，P.，Heibel，G.，Braslavsky，S. E、Schaffner，K.，& Schrader，B.（1992）Biochemistry 32，7957 - 7962），现在已经发现是错误的。
The parent states of the 124-kDa phytochrome (phy A from Avena sativa) and intermediates of its photocycle were studied by low-temperature Fourier-transform resonance Raman spectroscopy: Spectra of the primary photoproducts I-700 and lumi-F and of the thermal intermediate meta-F have been obtained for the first time. The spectra of the stable photochromic forms of photochrome, P-r and P-fr, presented in this work are significantly better in signal-to-noise ratio and resolution than previously published spectra, demonstrating the distinct advantages of our experimental approach. The high spectral quality allows for the identification of subtle details of the vibrational band pattern so that the resonance Raman spectra, which have been measured from samples in H2O and D2O, constitute a solid basis for the structural analysis of the various forms of phytochrome. Notwithstanding the current uncertainty in the vibrational assignment of many resonance Raman bands, the spectral changes of the tetrapyrrole chromophore can plausibly be interpreted in terms of conformational changes at two different methine bridges, i.e., torsions around two single bonds and the E/Z isomerization of a double bond. Within the framework of this interpretation, which is based on a vibrational analysis of biliverdin dimethyl ester (Smit, K., Matysik, J., Hildebrandt, P., and Mark, F. (1993) J. Phys. Chem. 97, 11887-11900), a consistent model is proposed to describe the molecular events in the chromophore during the photocycle. The involvement of a proton transfer in the primary photoprocess of P, can safely be ruled out. However, previous conclusions concerning the chromophore protonation in the individual states appear premature at the present state of the vibrational assignment. In particular, the attribution of a broad band at 1100 (-1) cm to the N-H out-of-plane bending of the protonated pyrrolenin nitrogen (Hildebrandt, P., Hoffmann, A., Lindemann, P., Heibel, G., Braslavsky, S. E., Schaffner, K., & Schrader, B. (1992) Biochemistry 32, 7957-7962) has now been found to be erroneous.