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Away from the edge: SAD phasing from the sulfur anomalous signal measured in-house with chromium radiation by Cheng Yang; J. W. Pflugrath; D. A. Courville; C. N. Stence; Joseph D. Ferrara is a Biochemistry, Genetics and Molecular Biology article available to read on EtoBox.

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Anomalous scattering with soft X-ray radiation opens new possibilities in phasing for macromolecular crystallography. Anomalous scattering from S atoms collected on an in-house chromium radiation source (λ = 2.29 Å) was used to phase the X-ray diffraction data of thaumatin (22 kDa) and trypsin (24 kDa) crystals. The contribution to the anomalous term, Δf'' = 1.14 e^−^, from sulfur for Cr __K__α radiation is doubled compared with that for Cu __K__α radiation, Δf'' = 0.56 e^−^. The direct-methods programs __RANTAN__ or __SHELXD__ successfully found sulfur positions using data sets with resolution limited to 3.5 Å. The statistical phasing program __SHARP__ was used to produce the electron-density maps using the sulfur anomalous signal alone at low resolution (∼3.5 Å). An interpretable electron-density map for each structure was obtained solely from the phases derived from single-wavelength anomalous dispersion (SAD) data obtained using Cr __K__α radiation. Much fewer data (that is, lower redundancy) are required for this sulfur SAD phasing procedure compared with the highly redundant data reported in the sulfur SAD phasing procedure with Cu __K__α radiation. Cr __K__α radiation can al

Who reads Away from the edge: SAD phasing from the sulfur anomalous signal measured in-house with chromium radiation?

Author

Cheng Yang; J. W. Pflugrath; D. A. Courville; C. N. Stence; Joseph D. Ferrara

Publisher

International Union of Crystallography; Blackwell Publishing Inc.; International Union of Crystallography (IUCr) (ISSN 0907-4449)

Published

2003

Language

EN

ISBN

9780907444909

Field

Biochemistry, Genetics and Molecular Biology (Life Sciences)