PROTEIN CRYSTALLOGRAPHY
AN INTRODUCTION
What is Protein Crystallography?
Various techniques give different and complementary information about protein structure and function. The primary structure (sequence) of a protein is determined by biochemical methods. The quaternary structure (overall shape) of protein molecules can be obtained using small angle scattering or, in the case of large particles, electron microscopy. However, to determine the secondary and tertiary structure detailed (high resolution) information is required about the arrangement of atoms within a protein. The main method used is protein crystallography which enables the recording of information down to atomic resolution (1.0 Å).Protein Crystallography at Daresbury Laboratory
Many human protein structures have been determined using the Protein Crystallography facilities at Daresbury. Many protein structures, from organisms that affect human well being, have also been determined here. They have led to drug designs that are currently bearing fruit in improving healthcare and the quality of life.
Protein crystallography experiments at Daresbury are performed using high energy X-rays from the Synchrotron Radiation Source. These X-rays strike the protein crystals, producing characteristic diffraction patterns. The recorded diffraction patterns are then analysed to determine structural information about the protein.
The Protein Crystallography Facility Group at Daresbury operates four experimental stations for users:
- Station 9.6 , Wavelength-shifter wiggler source, High intensity monochromatic beam, wavelength 0.87Å. Closed to users from 2007
- Station 10.1, Multipole wiggler source, High intensity rapidly and widely tunable beam for MAD/SAD.
- Station 14.1, Multipole wiggler source, High intensity monochromatic beam, wavelength 0.98Å or 1.488Å. Closed to users from 2007
- Station 14.2, Multipole wiggler source, High intensity monochromatic beam, tunable around the Selenium absorption edge (0.98 Å). Closed to users from 2007
In addition the group previously operated two other stations, which are no longer available for users:
- Station 7.2, Bending magnet source, monochromatic beam, wavelength 1.488Å.
- Station 9.5, Wavelength-shifter wiggler source, rapidly tunable beam.
The stations all feature sophisticated optical, mechanical and electronic equipment to ensure that a small (~0.2 mm) X-ray beam intersects with a similarly sized protein crystal, as well as fast detectors for recording the diffraction patterns and powerful computing facilities for analysing data. Stations 10.1 and 14.2 also feature robotic sample-changing facilities. It is the responsibility of the staff at Daresbury to maintain this equipment so that our users can collect the best data possible.
Left to right: protein crystal, diffraction
pattern and a fast readout detector on 10.1
Two members of staff per station are also dedicated to providing technical and scientific support to users during their experiments. This includes training in the safe and effective use of the stations, assistance when faults occur with the station equipment and advice on the best way to achieve the experimental objectives. In addition to the PX facilities, a Structural Biology Laboratory (SBL) is available for users to prepare their samples immediately before their allocated beamtime.
Scientific collaborations between staff and users have proved very fruitful. Recent successes include the light-harvesting complex, which is responsible for trapping and transporting energy in bacteria and numerous lectin structures. Lectins exist in all living things and have the potential for binding and deactivating viruses, such as HIV.
Left
to right: Crystal-mounting robot on 14.2, the Biology & Medicine
College station scientists and the retroviral capsid domain solved on 14.2
and featured on the cover of Nature
The major breakthrough in recent years for the pharmaceutical industry was the determination of the complete human genome. There are ~100,000 different genes in this genome, with similar numbers in other organisms of interest in medicine and biotechnology. Faults in any one could produce a range of effects, either desirable or unfavourable.
The Protein Crystallography facilities at Daresbury are required to help with the massive effort of trying to deal with all these gene products, their naturally occurring variants, and the multitude of interactions between them. This is an imperative first step in the long quest to improve the quality of care for the sick, and the quality of life in general.
Read more detailed information about crystallography and protein structure
Access to the facilities on offer is controlled by a set of rules agreed upon by the Laboratory and its main patrons, The UK Research Councils and the EU Large Scale Facilities Program. The User Liaison Office will provide copies of these rules to interested people. Other researchers can still access the facilities under the same rules that apply to industrial users.
Industrial users may use the straightforward data collection services, where the expert industrial would be assisted by a DL employee during data acquisition. There are extensions to this service, at negotiable rates, like data processing, i.e. delivery of data sets, or even full crystallographic structure solution and refinement.
Please address comments or enquiries to: J.M.Nicholson@dl.ac.uk
