Suite of three protein crystallography beamlines with single superconducting bend magnet as the source

Abstract

SynopsisThree near identical protein crystallography beamlines with a single 6 Tesla peak field superconducting dipole bend magnet as the source have been built at the 1.9 GeV Advanced Light Source. The design and performance of this new facility is described. AbstractAt the Advanced Light Source (ALS), three protein crystallography (PX) beamlines have been built that use as a source one of the three 6 Tesla single pole superconducting bending magnets (superbends) that were recently installed in the ring. The use of such single pole superconducting bend magnets enables the development of a hard x-ray program on a relatively low energy 1.9 GeV ring without taking up insertion device straight sections. The source is of relatively low power, but due to the small electron beam emittance, it has high brightness. X-ray optics are required to preserve the brightness and to match the illumination requirements for protein crystallography. This was achieved by means of a collimating premirror bent to a plane parabola, a double crystal monochromator followed by a toroidal mirror that focuses in the horizontal direction with a 2:1 demagnification. This optical arrangement partially balances aberrations from the collimating and toroidal mirrors such that a tight focused spot size is achieved. The optical properties of the beamline are an excellent match to those required by the small protein crystals that are typically measured. The design and performance of these new beamlines are described.

SIBYLS — a SAXS and Protein Crystallography Beamline at the ALS

“…The change in focus location is achieved by slight change of the M2 tilt angle. Previously [1] we found that when the toroidal mirror is used with parallel illumination in the vertical and a 2:1 demagnification in the horizontal, then the main aberrations cancel out and a high quality image results. This has been determined to be due to the vanishing of the astigmatic coma for the 2:1 horizontal demagnification case [5].…”

“…The basic beamline layout was the same employed on the previous PX superbend beamlines [1]. The beamline design adopted is shown schematically in Fig.1.…”

“…Both mirrors are coated with 8nm of Rhodium over 25nm of Platinum and operated at 4.5 mrad grazing angle. This bilayer coating allows for suppression of the Platinum L edges in the (11-14)KeV range whist extending the mirror cut off ~2.5KeV beyond what one would obtain from a single Rhodium coated mirror [1]. The first crystal is an internally water cooled flat Si(111) crystal, the first multilayer is a side cooled flat with 150 layer pairs of Mo/B 4 C, d spacing = 2.4nm.…”

“…The beamline is a development on the previous three successful PX beamlines [1] deployed at the ALS with the addition of having a monochromator with both Si(111) and multilayer monochromator elements and an end station capable of carrying out PX and static and time resolved SAXS. The x-ray source is one of the three 5 Tesla superbend dipoles recently installed around the ALS.…”

Mycobacterium tuberculosis RpfE crystal structure reveals a positively charged catalytic cleft

“…Diffraction data were collected at the Lawrence Berkeley National Laboratory Advanced Light Source Beamline 8.3.1. 21 Data were scaled using HKL2000. The PHENIX software suite 22 was used for model building by molecular replacement using the RpfB homolog (3EO5 in PDB) as the search model.…”