Fast Detection Allowing Analysis of Metalloprotein Electronic Structure by X-ray Emission Spectroscopy at Room Temperature

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• 作者：Katherine M. Davis ; Brian A. Mattern ; Joseph I. Pacold ; Taisiya Zakharova ; Dale Brewe ; Irina Kosheleva ; Robert W. Henning ; Timothy J. Graber ; Steve M. Heald ; Gerald T. Seidler ; Yulia Pushkar
• 刊名：The Journal of Physical Chemistry Letters
• 出版年：2012
• 出版时间：July 19, 2012
• 年：2012
• 卷：3
• 期：14
• 页码：1858-1864
• 全文大小：347K
• 年卷期：v.3,no.14(July 19, 2012)
• ISSN：1948-7185

文摘

The paradigm of 鈥渄etection-before-destruction鈥?was tested for a metalloprotein complex exposed at room temperature to the high X-ray flux typical of third-generation synchrotron sources. Following the progression of the X-ray-induced damage by Mn K尾 X-ray emission spectroscopy, we demonstrated the feasibility of collecting room-temperature data on the electronic structure of native Photosystem II, a trans-membrane metalloprotein complex containing a Mn₄Ca cluster. The determined nondamaging observation time frame (about 100 ms using a continuous monochromatic beam, with a deposited dose of 1 脳 10⁷ photons/渭m² or 1.3 脳 10⁴ Gy, and about 66 渭s in pulsed mode using a pink beam, with a deposited dose of 4 脳 10⁷ photons/渭m² or 4.2 脳 10⁴ Gy) is sufficient for the analysis of this protein鈥檚 electron dynamics and catalytic mechanism at room-temperature. Reported time frames are expected to be representative for other metalloproteins. The described instrumentation, based on the short working distance dispersive spectrometer, and experimental methodology are broadly applicable to time-resolved X-ray emission analysis at synchrotron and X-ray free-electron laser light sources.

Keywords:

X-ray emission spectroscopy (XES); Photosystem II; time-resolved; X-ray induced damage; manganese