散射實驗在蛋白質結構及動態之研究

Abstract

過去五年來，新一族同步輻射加速器開始加入運轉，其低束散度(low emittance)的特質，使利用高亮度及同調性(coherence)的X光實驗開始受到極大的注意，未來幾年，美、日、德等國之自由電子雷射(free electron laser)更將達到硬X光的波段，也開始開啟百年來無法解決的X光相位(phase)實驗。此完全同調的X光光源使X光結構研究不再侷限於有序(order)的晶體條件下。本計畫主旨在利用本研究群過去五年發展的X光散射及影像實驗技術，進行蛋白質及細胞之研究。本期計畫之實驗尤其將集中在於一個特定蛋白質: Nitric Oxide Synthase的結構及動態之了解。

The availabilities of x-ray sources from low-emittance synchrotrons and new x-ray free electron lasers allow researchers to explore new class of x-ray scattering measurements by the utilization of high brilliance and high degree of coherence of the X-ray beam. In couple with the new developments in x-ray scattering methodologies, such as over sampling methods of phase problem and iterative phase retrieve methods for phase imaging, have opened up exciting opportunities in x-ray science to solve the long standing structural problems of disordered or partially disordered systems in condensed matter and biology. In the past several years, our work has been focused on the implementation of x-ray techniques for the studies of nano materials and biological systems, including small-angle X-ray scattering (SAXS), transmission X-ray microscopy (TXM), and coherent diffractive imaging (CDI). In the next three years, my research will be highly aimed to advance our structural understanding of one complex protein system with very important biomedical functions: the Nitric Oxide Synthase (NOS), a class of enzymes which produce singling molecule NO. Other proteins and cell systems may also be explored using these newly available X-ray probes.