Photo-induced dynamics of proteins

利用光克尔门技术，在室温下研究了光敏黄蛋白水溶液中光诱导动力学的早期阶段.显着的振荡成分已直接观察到的时间分辨率为180 fs和光谱分辨率为5 nm。对每个波长处振荡的相位进行时间映射揭示了每个振荡被限制在相应的窄光谱区域中，其周期和振幅分别为500-800 fs和100-200 cm-2<-1>。由于每个组分的平均光谱位置似乎与分子的振动能有关，因此振荡组分可能是发色团分子内振动和周围蛋白质运动的组合。为了更定量地研究光循环过程中蛋白质运动的动力学，我们构建了时域THz光谱系统。来自Ti;Sapphire振荡器（MaiTai，Spectra Physics）的飞秒激光脉冲用于发射和检测THz辐射。在GaAs晶片上的蝴蝶结形金漆天线用于发射器，而在GaAs晶片上的偶极形金漆天线用于检测器。发射极上施加2 KHz ± 20 V交流偏置电压。通过锁定放大器检测预放大的THz信号。为了评价该太赫兹光谱系统，测量了水-甲醇混合物和水-乙醇混合物在较宽浓度比范围内的反射光谱。我们成功地得到了混合溶液的介电振幅和相位的浓度依赖性。时域太赫兹光谱的光活性蛋白质的过程中，由可见光激光脉冲触发的光周期，现在正在取得进展。

The early stage in the photoinduced dynamics of photoactive yellow protein in aqueous solution has been investigated at room temperature by the femtosecond luminescence spectroscopy using an optical Kerrgate technique. Remarkable oscillatory components have been directly observed with the time resolution of 180 fs and the spectral resolution of 5 nm. Mapping the phase of oscillations in time at each wavelength reveals that each oscillation is restricted in the respective narrow spectral region, the period and amplitude of which are 500-800 fs and 100-200 cm^<-1>, respectively. Since the mean spectral position of each component seems to be related to the molecular vibrational energy, the oscillatory components are possibly attributed to the combination of the intramolecular vibrations of the chromophore and the surrounding protein motionsIn order to investigate the dynamics of protein motions in the course of the photo cycle more quantitatively, a time-domain THz spectroscopic system has been constructed. Femtosecond laser pulses from a Ti;Sapphire oscillator (MaiTai, Spectra Physics) are used to emit and detect THz radiation. A bowtie-shaped gold-paint antenna on a GaAs wafer is used for the emitter, while a dipole-shaped gold-paint antenna on a GaAs wafer is used for the detector. A 2 KHz, ±20V ac bias voltage is applied to the emitter. A pre-amplified THz signal is detected by a lock-in-amplifier. In order to evaluate the THz spectroscopic system, reflection spectra of water-methanol mixture and waterethanol mixture in a wide range of the concentration ratio have been measured. We have successfully obtained the concentration dependence of dielectric amplitude and phase for the mixture solutions. Time-domain THz spectroscopy for photoactive proteins in the course of the photo cycle triggered by a visible laser pulse is now progressing.