The Structural Biology Center 19ID undulator beamline: facility specifications and protein crystallographic results

Abstract

The 19ID undulator beamline of the Structure Biology Center has been designed and built to take full advantage of the high flux, brilliance and quality of X-ray beams delivered by the Advanced Photon Source. The beamline optics are capable of delivering monochromatic X-rays with photon energies from 3.5 to 20 keV (3.5-0.6 A wavelength) with fluxes up to 8-18 x 10(12) photons s(-1) (depending on photon energy) onto cryogenically cooled crystal samples. The size of the beam (full width at half-maximum) at the sample position can be varied from 2.2 mm x 1.0 mm (horizontal x vertical, unfocused) to 0.083 mm x 0.020 mm in its fully focused configuration. Specimen-to-detector distances of between 100 mm and 1500 mm can be used. The high flexibility, inherent in the design of the optics, coupled with a kappa-geometry goniometer and beamline control software allows optimal strategies to be adopted in protein crystallographic experiments, thus maximizing the chances of their success. A large-area mosaic 3 x 3 CCD detector allows high-quality diffraction data to be measured rapidly to the crystal diffraction limits. The beamline layout and the X-ray optical and endstation components are described in detail, and the results of representative crystallographic experiments are presented.

Figure 1

Schematic diagram showing the relative location of the optical components in 19ID. [Indicated distances are from the center of the straight section, not from the center of the radiation source (undulator) as in the text.]

Figure 2

Schematic diagram of the endstation components, including X-ray beam-position monitors, timing shutter, attenuators, beam stop, sample and CCD detector.

Figure 3

Photograph of the sample area showing the κ goniometer (center), beam stop (left of sample), sample cooler (center right), objective lens of the alignment microscope and output of fiber-optic lighting (top right). The beam comes from the right through the beam transport tube (right center; scatter guard plug not visible).

Figure 4

Detector support with the ADSC Quantum 315 detector moved back for free access to the goniometer, displays of alignment cameras (center back), local beamline control terminal (left), goniometer with cameras and cold stream (right) and fluorescence detector (right foreground). The beam direction is from right to left.

Figure 5

Resolving power of the mosaic 3 × 3 CCD detector SBC2 demonstrated by the recording of a diffraction pattern from the 50S ribosomal subunit (orthorhombic space group C222₁, a = 212, b = 301, c = 576 Å). Resolution markers (circles), the resolution limit (upper enlargement) and the spatial resolution (lower enlargement) of the measurement are shown. (Courtesy of Dr T. Steitz, Yale University.)

Figure 6

Screen shot of the SBCcollect graphical user interface.

Figure 7

Statistics of the Protein Data Bank structure depositions using data collected at beamline 19ID plotted versus year of deposition. (For 2005, data are incomplete.)

Figure 8

Contributions of the Protein Data Bank deposits to the Protein Structure Initiative program by US synchrotron beamlines.

Figure 9

1.7 Å SAD map of membrane-associated lipoprotein-9 GmpC from Staphylococcus aureus contoured at 1σ. A single Se atom was used to phase the 297 residues protein (Williams et al., 2004).