Protein crystals are extremely sensitive and poorly defined, due to the extremely large proportion of water within their structures. As a result, protein structures are ‘floppy’ and the X-ray diffraction data is typically of a much lower resolution quality compared to a small molecule structure.
At the same time, the number of atoms present in a protein structure is extremely large and the data (Bragg reflections) to be collected is very closely packed together.
Protein crystallographers rely on the strongest X-ray sources to combat the issues of air sensitivity, small crystals, low diffraction and densely packed reflections. Traditionally, a high brilliance synchrotron has been used to measure full protein data leading to protein structure determination, whilst home laboratory instruments have been used for protein screening to identify the preferred crystals for measurement at the synchrotron.
High brilliance X-ray sources, such as the Excillum MetalJet have made a greater number of protein structures and experiments possible in the home laboratory, thereby accelerating research with ease of access and convenience. Using the high brilliance MetalJet X-ray source makes weak diffraction data stronger, reducing experiment times and potentially reducing sample degradation. The narrow, focused X-ray beam is ideally suited to measuring even the smallest protein crystals, providing compact and well-defined reflections. The higher intensity MetalJet X-rays typically extend the angular resolution limit of the visible protein data collected and provide more precise reflection positions and intensities, leading to higher resolution protein structures.
“The X-ray source helps a lot, in some cases its use replaces the need for synchrotron. Our main goal with purchasing and using the MetalJet is focused on studying smaller crystals. Working with 30 micron crystals is no longer an obstacle”.
Dr. Jan Dohn Alek, Institute of Biotechnology, Czech Academy of Sciences, BIOCEV