Development of a new detection method of time resolved circular dichroism

圆二色谱(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，但到目前为止，其适用性一直相当有限。其中一个原因是用CD光谱仪进行时间分辨研究比较困难。我们开发了两种技术来检测时间分辨的CD信号。1.对商用CD光谱仪进行了改进，以获得毫秒的时间分辨率。光谱仪直接从光谱仪检测CD信号，没有进行偏振调制。2.传统的CD光谱仪采用左右偏振光强度的时间调制。我们开发了一种利用偏振光强的空间调制来检测CD的新方法。利用一种非线性光学光谱仪--瞬变光栅法对CD信号进行检测。我们发现，这种方法的灵敏度和时间分辨率(10 Ns)都是很好的，因为它是背景自由检测的。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.