Characteristics of a flat multiwire area detector for protein crystallography

Abstract

A flat, relatively thin (9 mm) xenon-filled multiwire proportional counter with two-dimensional, 2/~s delay line readout of a 270 x 300 mm active area has been developed for use as a position-sensitive area X-ray detector in the 8 keV energy region (Cu Ka) used in crystallographic structure work with large biological molecules. Its quantum detection efficiency for 8 keV Xray photons is about 0.5, a value which is spatially uniform to within _+ 2%. Its dead-time loss fraction at a typical data collection rate of 30 000 photons s-1 is 12%. The detector has spatial resolution for X-rays of 0.6 mm FWHM in the horizontal direction and 2 ram, the anode wire spacing, in the vertical direction. The effects of parallax are found to be limited and do not seriously increase the apparent size of the diffracted beams. The position sensitivity of this detector is geometrically linear to within 0-5 mm across its active surface. Routine maintenance of the detector requires the attention of a skilled technician but is not time consuming. For four years, this detector has been used to measure millions of reflection intensities from crystals of many different proteins. The down time due to the detector has averaged less than four days per year, considerably less than the down time of other components of the data collection system. Four new protein structures have now been solved using data from this detector. Also, a considerable amount of data have been collected at higher resolution or at different temperatures with crystals of other proteins.

Determination of three crystal structures of canavalin by molecular replacement

“…The cubic crystals are not seen to coexist with or transform into others. For data collection crystals were mounted by conventional means in quartz capillaries and intensities collected at 291 K using a two-panel multiwire areadetector system manufactured by San Diego Multiwire Systems equipped with a 20 table (Hamlin et al, 1981;Xuong, Nielson, Hamlin & Anderson, 1985). The X-ray source was a Rigaku RU-200 rotating anode operated at 45 kV and 145 mA and fitted with a Supper Co. graphite-crystal monochromator to yield Cu Ka radiation.…”

Crystal structures of the myristylated catalytic subunit of cAMP‐dependent protein kinase reveal open and closed conformations

“…All of the mammalian cAPK crystal diffraction data were collected at 4°C with graphite monochromated CuKa X-rays from a Rigaku Ru-200 rotating anode diffractometer at the UCSD Research Resource equipped with two Xuong-Hamlin multiwire area detectors (Hamlin et al, 1981 ;Xuong et al, 1985). Statistics for the three data sets are summarized in Table 1.…”

Crystal structures of the active site mutant (Arg‐243 → Ala) in the T and R allosteric states of pig kidney fructose‐1,6‐bisphosphatase expressed in escherichia coli

“…Because of the detector setup, reflections were collected to 2.2 A, but usable data extended to about 2.75 A. The diffraction data were merged using the software provided by Area Detector Systems (Hamlin et al, 1981). A scale factor was calculated for multiple measurements and symmetry-related reflections.…”