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Publication Abstract from PubMed

Recently, the demands of high-throughput macromolecular crystallography have driven continuous improvements in phasing methods, data-collection protocols and many other technologies. Single-wavelength anomalous scattering (SAS) phasing with chromium X-ray radiation opens a new possibility for phasing a protein with data collected in-house and has led to several successful examples of de novo structure solution using only weak anomalous scatterers such as sulfur. To further reduce data-collection time and make SAS phasing more robust, it is natural to combine selenomethionine-derivatized protein (SeMet protein) with Cr Kalpha radiation to take advantage of the larger anomalous scattering signal from selenium (f = 2.28 e(-)) compared with sulfur (f = 1.14 e(-)). As reported herein, the crystal structure of a putative chorismate mutase from Clostridium thermocellum was determined using Se-SAS with Cr Kalpha radiation. Each protein molecule contains eight selenomethionine residues in 148 amino-acid residues, providing a calculated Bijvoet ratio of about 3.5% at the Cr Kalpha wavelength. A single data set to 2.2 A resolution with approximately ninefold redundancy was collected using an imaging-plate detector coupled with a Cr source. Structure solution, refinement and deposition to the Protein Data Bank were performed within 9 h of the availability of the scaled diffraction data. The procedure used here is applicable to many other proteins and promises to become a routine pathway for in-house high-throughput crystallography.

Away from the edge II: in-house Se-SAS phasing with chromium radiation.,Xu H, Yang C, Chen L, Kataeva IA, Tempel W, Lee D, Habel JE, Nguyen D, Pflugrath JW, Ferrara JD, Arendall WB 3rd, Richardson JS, Richardson DC, Liu ZJ, Newton MG, Rose JP, Wang BC Acta Crystallogr D Biol Crystallogr. 2005 Jul;61(Pt 7):960-6. Epub 2005, Jun 24. PMID:15983419^[1]

From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine.