ID14-4 Macromolecular Crystallography MAD Beamline

 ID14-4 is now back in user mode, check 'ID14-4 Updates' page for recent problems and fixes.

Contact Tel: +33(0)47688 +ext Andrew McCarthy Scientist in charge +33(0)47620 7276 ID14-4 Control Cabin 2322 email to ID14-4

Synopsis

Beamline ID14 is an undulator beamline on a high ß section dedicated to macromolecular crystallography. Station ID14-4 is an end station of the ID14 beamline and has been in continuous operation since 1998. It provides high brilliance around 13.2 keV, as well as wide tunability between 9.6 keV and 14.5 keV. The station is available for conventional single wavelength data collection and also for Single and Multiple-wavelength Anomalous Diffraction (SAD/MAD) experiments, which form the majority of the station's experiments.

The beamline is designed to achieve the following:

• High brilliance at around 13.2 keV.
• A large tunable energy-range i.e.9.6 keV < E < 14.5 keV for SAD/MAD experiments.
• A very good energy resolution (i.e ~0.3eV) to scan an element's absorption edge.
• A low background reached by a complete vacuum environment (p = 5 x 10^-3 Torr) and windowless operation.
• A Q315r ADSC CCD detector for quality high-speed data collection.

Scientific Applications

The single anomalous diffraction (SAD) and multiwavelength anomalous diffraction (MAD) techniques have become widely used and important tools in macromolecular structure determination. The Bijvoet pairs are measured at a single wavelength in a SAD experiment and at several wavelengths near the absorption edge in the MAD techniques. By tuning the incident X-ray energy close to the atomic absorption edge energies, the atomic scattering amplitudes are changed and consequently their contribution to the scattering. These anomalous and dispersive differences in the measurement of a reflection contain information about the structure of the anomalously scattering atoms and the relation between the anomalous scattering atoms and the rest of the structure. Thus the calculation of experimental phases can be carried out and a model built to fit the electron density. ID14-4 was principally designed for this purpose.

• A highly accurate energy resolution, ~0.3eV
• An XFlash flouresence detector from Rontec with excellent energy resolution and high sensitivity for florescence signal detection.
• A Q315r ADSC detector for quality data collection at high speed.
• Attenuation of beam is possible to reduce radiation damage, especially for protein crystals.

The success of undulator beamlines in macromolecular crystallography is also allowing more ambitious projects to be pursued. We are always trying to expand and improve ID14-4 and ID14-4 is now not only of interest for SAD and MAD techniques, but also for areas requiring high intensity X-rays such as:

• Large macromolecular assemblies (Ribosomes and RNA polymerases)
• Virus crystals
• Weakly diffracting crystals
• small crystals, good visualization and a small beam size allow data to be collected on small crystals (down to 30 microns)

Recent Structures solved on ID14-4 (2/11/2007)

Clantin, B., Delattre, A. S., Rucktooa, P., Saint, N., Meli, A. C., Locht, C., Jacob-Dubuisson, F., & Villeret, V. (2007) Science 317, 957-961.

Martinez-Molina, D., Wetterholm, A., Kohl, A., McCarthy, A. A., Niegowski, D., Ohlson, E., Hammarberg, T., Eshaghi, S., Haeggström, J. Z., Nordlund, P. (2007) Nature 448, 613-616.

Miled, N., Yan, Y., Hon, W. C., Perisic, O., Zvelebil, M., Inbar, Y., Schneidman-Duhovny, D., Wolfson, H. J., Backer, J. M., & Williams, R. L.  (2007) Science 317, 239-242.

Rock, F. L., Mao, W., Yaremchuk, A., Tukalo, M., Crépin, T., Zhou, H., Zhang, Y. K., Hernandez, V., Akama, T., Baker, S. J., Plattner, J. J., Shapiro, L., Martinis, S. A., Benkovic, S. J., Cusack, S., Alley, M. R. (2007) Science, 316, 1759-1761.

For a complete list of all the structures solved at ID14-4 see the BioSync webpage.