Synopsis

Beamline ID14-EH3 is a fixed wavelength beamline for Small Angle X-ray Scattering (SAXS) experiments of protein in solution with goal to determine their 3-dimensional structures in a natural state with a 'low' resolution (~nm).  It is one of the 4 stations on ID14.

The beamline has been re-built from MX to bio-SAXS beamline with the user operation successfuly started at November 2008.

The beamline is designed to achieve the following:

• routine data collection on protein in solution in the temperature range from 5 to 50° C ;
• sample handing equipment with off-axis visualisation, sample cell is a 2 mm diameter quartz capillary with 10 micron wall thickness;
• automated data collection and processing using automated sample changer of a storage capacity of 8 samples (0.2 mL PCR tubes) and 3 buffers (1.5 mL tubes); processing pipeline at the time being semi-automatic

Applying for Bio-SAXS Beam-time

Application for beam-time will follow a rapid access model and can be made at ANY time. Those who wish to apply (including members of ESRF MX BAG Groups) should use the mechanism for:

MXnon-BAGproposal

Where it must be clearly indicated in the title of the proposal that the application is for Bio-SAXS beamtime on ID14-3.

Scientific Applications

The SAXS is a unique method for studying low resolution structure and structural transitions of individual proteins and large macromolecular complexes in solution. The presence of a biologically-oriented SAXS beamline at the ESRF will enable determination of low resolution shapes of proteins, which cannot be crystallised (or of those, which have been crystallised, in which case the shapes can be used as masks for low resolution phasing) and validation of MX models in solution. The cutting-edge experiments performed on small sample volumes in parallel with MX applications will provide valuable complementary information on the structure of targets in solution.

Using SAXS to model structures:

•  using known atomic resolution structure of individual domains: SAXS used to determine the relative orientation and placement of these domains in a complex (rigide body modeling)
•  direct comparison of crystallographic structures (theoretical solution scattering pattern can be calculated from the atomic coordinates) with SAXS data
•  ab-initio envelope reconstruction: three-dimensional envelope generated from the one-dimansional SAXS curve

Figure shows X-ray solution scattering curves computed from atomic models of 25 different proteins with molecular masses between 10 and 300 kDa.  

Technical  details

The working energy of ID14-EH3 is 13.32keV (lambda = 0.931 Angstrom). Experimental hutch is equipped with a marble table housing the modulable-length fligth tube, 2D detector  and a sample handing equipment. The achievable q-range is at the time being limitted to 0.1 - 5 nm^-1, which corresponds to the biggest measurable Rg (radius of gyration) of the investigated particle of 10 nm. An automatic sample changer and processing software allow data collection and data analysis pipeline.

SAXS/SANS Platform for Structural Biology

The establishment of this integrated platform allows to CISB members and associates as well as external users of the ESRF and ILL access to both the new experimental facility for SAXS at the ESRF and existing facilities for small angle neutron scattering (SANS) at the Institut Laue- Langevin (ILL).

For those ILL proposals which have signalled a wish for ESRF SAXS time and which are awarded beam time by the ILL colleges, they will receive the official decision from the ILL which will at the same time tell them to now go and fill in the ESRF Bio-SAXS Rolling application. The review by the respective ILL and ESRF colleges/committees will be co-ordinated, as well as scheduling of successful SANS and SAXS time.

First users using both facilities are expected this summer 2010.

SANS uses the dramatic difference in the interaction of neutrons with hydrogen atoms ¹H and deuterons ²H and allows contrast variation studies on 2 (and more) component systems (as ribosome, DNA-protein complexes, ...) and is comlementary to SAXS.

For further details see SAXS/SANS PSB platform web page