Development of a new detection method of time resolved circular dichroism

圆二色性（CD）是研究蛋白质等分子结构的一种非常有效的技术。然而，尽管具有潜在的能力，但迄今为止其适用性相当有限。其中一个原因是CD光谱仪难以进行时间分辨研究。我们开发了两种检测时间分辨CD信号的技术。对商用CD光谱仪进行了改进，以获得毫秒级的时间分辨率。不经过偏振调制，直接从光谱仪中检测到CD信号。传统的CD光谱仪使用左、右偏振光强度的时间调制。我们开发了一种利用空间调制偏振光强度的CD检测方法。采用非线性光谱学中的瞬态光栅技术对CD信号进行检测。结果表明，由于无背景检测，该系统具有良好的灵敏度和10ns的时间分辨率。我们现在正计划将这种方法应用于一些生物分子的结构变化。

The circular dichroism (CD) is a very powerful technique to study molecular structures such as proteins. However, in spite of the potential capability, the applicability has been rather limited so far. One of the reason is that it is difficult to use the CD spectrometer for the time resolved study. We have developed two techniques to detect the time-resolved CD signal.1.A commercial CD spectrometer was improved to obtain a millisecond time resolution. The CD signal was detected directly from the spectrometer without thepolarization modulation.2.The conventional CD spectrometer uses a temporal modulation of the right-and left-polarized light intensity. We developed a new CD detection method using a spatial modulation of the polarized light intensity. The CD signal was detected by one of nonlinear optical spectroscopies, the transient grating technique. It was found that the sensitivity and the time resolution (10 ns) are excellent bacause of the back-ground free detection.We are now planning to apply this method to structural changes of some biological molecules.