Ciao Roberto B. You might want to cite:
Acta Crystallogr D Biol Crystallogr. 2010 Sep;66(Pt 9):988-1000. Epub 2010 Aug 13. Inclusion of weak high-resolution X-ray data for improvement of a group II intron structure. Wang J. Department of Molecular Biophysics and Biochemistry, Yale University, New Haven, CT 06520, USA. jimin.w...@yale.edu Abstract It is common to report the resolution of a macromolecular structure with the highest resolution shell having an averaged I/sigma(I) > or = 2. Data beyond the resolution thus defined are weak and often poorly measured. The exclusion of these weak data may improve the apparent statistics and also leads to claims of lower resolutions that give some leniency in the acceptable quality of refined models. However, the inclusion of these data can provide additional strong constraints on atomic models during structure refinement and thus help to correct errors in the original models, as has recently been demonstrated for a protein structure. Here, an improved group II intron structure is reported arising from the inclusion of these data, which helped to define more accurate solvent models for density modification during experimental phasing steps. With the improved resolution and accuracy of the experimental phases, extensive revisions were made to the original models such that the correct tertiary interactions of the group II intron that are essential for understanding the chemistry of this ribozyme could be described. Even if you do not take full advantage of what J. Wang suggests in the paper you can mention that in terms of 'common practice' an I/sigma(I) = 2 is fine. Ciao Roberto S. On 3 Mar 2011, at 11:29, Roberto Battistutta wrote: > Dear all, > I got a reviewer comment that indicate the "need to refine the structures at > an appropriate resolution (I/sigmaI of >3.0), and re-submit the revised > coordinate files to the PDB for validation.". In the manuscript I present > some crystal structures determined by molecular replacement using the same > protein in a different space group as search model. Does anyone know the > origin or the theoretical basis of this "I/sigmaI >3.0" rule for an > appropriate resolution? > Thanks, > Bye, > Roberto. > > > Roberto Battistutta > Associate Professor > Department of Chemistry > University of Padua > via Marzolo 1, 35131 Padova - ITALY > tel. +39.049.8275265/67 > fax. +39.049.8275239 > roberto.battistu...@unipd.it > www.chimica.unipd.it/roberto.battistutta/ > VIMM (Venetian Institute of Molecular Medicine) > via Orus 2, 35129 Padova - ITALY > tel. +39.049.7923236 > fax +39.049.7923250 > www.vimm.it
