Getting the most out of X-ray home sources

Acta Crystallogr D Biol Crystallogr. 2005 Aug;61(Pt 8):1022-30. doi: 10.1107/S0907444905012989. Epub 2005 Jul 20.

Abstract

The structures of a 14 kDa phospholipase, an 18 kDa proteinase inhibitor and a novel glycoside hydrolase with molecular weight 60 kDa were solved using the SAD technique and the effects of the amount of anomalous signal, completeness and redundancy of data on heavy-atom substructure determination, phasing and model building were analyzed. All diffraction data sets were collected on a Cu-anode X-ray home source. The structure of the phospholipase was obtained using the anomalous scattering contribution from its 16 S atoms. Three-dimensional models for the other two macromolecules were obtained using the anomalous contribution of I atoms rapidly incorporated into the crystal through the quick cryo-soaking method of derivatization. These results were used to discuss the application of sulfur- and iodine-SAD approaches in combination with X-ray home sources for high-throughput protein crystal structure solution. The estimates of the anomalous signal from S atoms in the gene products of four genomes are given and the prospects for increasing the anomalous contribution using longer wavelengths (e.g. from a chromium home source) and quick cryo-soaking derivatization are discussed. The possibility of rapidly preparing tangible home-source isomorphous derivatives suggests that this approach might become a valuable tool in the future of post-genomic projects.

MeSH terms

  • Aspergillus / enzymology
  • Bauhinia / chemistry
  • Crystallization
  • Crystallography, X-Ray / methods*
  • Genome, Bacterial
  • Glycoside Hydrolases / chemistry*
  • Models, Molecular
  • Phospholipases A / chemistry*
  • Protease Inhibitors / chemistry*
  • Sulfur / chemistry
  • X-Rays

Substances

  • Protease Inhibitors
  • Sulfur
  • Phospholipases A
  • Glycoside Hydrolases