MAD data collection – current trends

Abstract

The multiwavelength anomalous dispersion (MAD) method of protein structure determination is becoming a routine technique in protein crystallography. The increased number of wavelength-tuneable synchrotron beamlines capable of performing challenging MAD experiments, coupled with the widespread availability of charge-coupled device (CCD) based X-ray detectors with fast read-out times have brought MAD structure determination to a new exciting level. Ultrafast MAD data collection is now possible and, with the widespread use of selenium in the form of selenomethionine for phase determination, the method is growing in popularity. Recent developments in crystallographic software are complementing the above advances, paving the way for rapid protein structure determination. An overview of a typical MAD experiment is described, with emphasis on the rates and quality of data acquisition now achievable at third-generation synchrotron sources.

Functional similarities between phage λ Orf and Escherichia coli RecFOR in initiation of genetic exchange

“…Diffraction data were collected at 100K at the 19ID beamline of the Advanced Photon Source (Argonne National Laboratory) as described (33). The threewavelength anomalous diffraction (MAD) data (peak, 0.9795 Å; inflection point, 0.9797 Å; high remote, 0.94656 Å) were collected to 2.5 Å from the selenomethionine-substituted protein crystal by using an inverse-beam strategy.…”

Functional and Structural Analysis of the Siderophore Synthetase AsbB through Reconstitution of the Petrobactin Biosynthetic Pathway from Bacillus anthracis

“…To obtain protein from both constructs, recombinant E. coli cells were grown using selenomethionine-containing enriched M9 medium (pink medium) under conditions known to inhibit methionine biosynthesis (35,36). Cell cultures were grown at 37°C to an A 600 nm of ϳ0.95 then cooled down to 18°C before adding selenomethionine and 0.5 mM isopropyl ␤-D-1-thiogalactopyranoside to induce and maintained at 18°C overnight.…”

The X‐ray crystal structure of PA1607 from Pseudomonas aureginosa at 1.9 Å resolution—a putative transcription factor

“…Diffraction data (Table 2) were collected at beamline 19ID of APS, Argonne National Laboratory, following the approach described earlier (Walsh et al 1999). The two-wavelength inversed beam MAD inflection and peak wavelengths up to 1.85 Å were collected from one Se-Met labeled protein crystal at 100 K with 4-sec exposure/1°/frame using a 180-mm crystalto-detector distance.…”