Phase Sensitive X-Ray Diffraction Imaging of Defects in Biological Macromolecular Crystals

Abstract

Conventional x-ray diffraction topography is currently used to map defects in the bulk of protein crystals, but the lack of sufficient contrast is frequently a limiting factor. We experimentally demonstrate that this barrier can be circumvented using a method that combines phase sensitive and diffraction imaging principles. Details of defects revealed in tetragonal lysozyme and cubic ferritin crystals are presented and discussed. The approach enabling the detection of the phase changes of diffracted x rays should prove to be useful in the study of defect structures in a broad range of biological macromolecular crystals.

Impurity effect on defect formation of protein crystals

“…On synchrotron facilities, X-ray topographic studies have been performed in recent years [10][11][12][13][14][15][16], but point defects in the protein crystals could not be observed because of the limit of spatial resolution of this method.…”

White beam Laue topography using a scintillator-CCD combination

“…Due to the advantage of high-resolution and real-time monitoring, the scintillator-CCD combination has been applied as a detector system to synchrotron X-ray topography [1][2][3] as well as microradiography [4][5][6][7]. For the best resolution the scintillator is orientated perpendicular to the diffracted beam and as a result the topograph is an orthographic projection of the sample [8].…”

X‐ray microscopy at the advanced photon source

“…Microdiffraction utilizing KB and ZP optics has become the tool of choice for study of crystal strain, stress, phase, and orientation. Lastly, powerful hybrid techniques have been demonstrated, such as coherent enhancement of the minute diffraction contrast of dislocations in weakly scattering protein crystals [Hu 2001]. …”