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Bulk-solvent correction in large macromolecular structures

Authors :: B. Rees
Marat Yusupov
Lasse Jenner
Institut de génétique et biologie moléculaire et cellulaire (IGBMC)
Centre National de la Recherche Scientifique (CNRS)-Institut National de la Santé et de la Recherche Médicale (INSERM)-Université Louis Pasteur - Strasbourg I
Université Louis Pasteur - Strasbourg I-Institut National de la Santé et de la Recherche Médicale (INSERM)-Centre National de la Recherche Scientifique (CNRS)
Source :: Acta Crystallographica Section D: Biological Crystallography, Acta Crystallographica Section D: Biological Crystallography, International Union of Crystallography, 2005, 61 (Pt 9), pp.1299-301. ⟨10.1107/S0907444905019591⟩
Publication Year :: 2005
Publisher :: International Union of Crystallography (IUCr), 2005.
Abstract: International audience; The estimation of the bulk-solvent contribution to the diffraction of a macromolecular crystal makes use of a solvent mask which delimits the bulk-solvent regions in the crystal. It is shown that the way this mask is usually defined in CNS contains a bias which can lead to absurd results in the case of very large structures, where the calculations can only be made on relatively coarse grids. A modified procedure is described and applied to 70S ribosome data at 5.5 A resolution. The B factor affecting the bulk solvent is also discussed. Even in this case of very high and widely variable atomic B factors, it seems sufficient to consider a constant and isotropic B factor for the bulk solvent. This is initially set to the average value of the atomic B factor, but can be refined.