Seminars Archive

Phasing using high intensity free-electron laser radiation

Abstract
X-ray free-electron lasers (XFELs) provide extremely bright X-ray pulses of femtosecond duration, that promise to revolutionize structural biology, as they can be used to collect diffraction data from (sub)micrometer-sized crystals while outrunning radiation damage. The high fluence of the XFEL pulses induces, however, severe electronic radiation damage to the sample, and especially the heavy atoms are strongly ionized by the X-ray radiation. I will show that a reduction of the effective scattering power of the heavy atoms inside a chemically modified protein, and of the sulfurs in a native protein has been experimentally observed, and how that can influence experimental phasing methods. I will describe new Radiation damage-Induced Phasing schemes at high intensity, and new quantitative tools to retrieve information about the effective ionization of the damaged atomic species and to improve the quality of serial crystallographic data