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Dear Ed Pozharski, Am 23.09.2009 um 15:48 schrieb Ed Pozharski: > Take a look at this: > > Brunger, A., DeLaBarre, B., Davies, J. & Weis, W. X-ray structure > determination at low resolution. ACTA CRYSTALLOGRAPHICA SECTION > D-BIOLOGICAL CRYSTALLOGRAPHY 65, 128-133 (2009). > > The paper quotes Wayne Hendrickson (says "submitted") regarding > "determinancy" point (i.e. where the number of observations becomes > equal to the number of flexible torsions (of course, in this extreme > case gemoetric restraints essentially become constraints and you don't > refine B-factrors at all. With 50% solvent this is ~5.4A, and you are > far from that limit. yes, but this is only in case of torsion angle refinement. For x,y,z the determinancy point is ~3 A. > > It is rather surprising that any reviewer anywhere would have doubts > about possibility to refine structural model at 3.4A. While I don't > know what the referee said *exactly*, but he/she may be unaware of > this > > http://www.rcsb.org/pdb/statistics/histogram.do?mdcat=refine&mditem=ls_d_res_high&minLabel=0&maxLabel=5&numOfbars=10&name=Resolution > > > > On Wed, 2009-09-23 at 12:48 +0000, hugh morgan wrote: >> Hi, >> We are attempting to address a referees comment concerning our >> data/parameter ratio for a 3.4 A structure. Although the ratio is >> only >> 0.5, the R/Rfree is 25/29, which seems acceptable. Ideally I would >> like to include a reference showing a graph or table of >> data:parameter >> vs resolution but I have been unable to find such a paper. Please >> could someone point me in the right direction. >> Thanks in advance >> >> Hugh >> >> P.S. It would be nice to know if this table has been published >> http://www-structmed.cimr.cam.ac.uk/Course/Basic_refinement/Refinement.html >> >> or something similar to this, which includes higher resolution >> structures >> http://dirac.cnrs-orleans.fr/plone/Members/hinsen/data-parameter-ratio-in-x-ray-structure-determination >> >> >> > -- ******************************************************* Dirk Kostrewa Gene Center, A 5.07 Ludwig-Maximilians-University Feodor-Lynen-Str. 25 81377 Munich Germany Phone: +49-89-2180-76845 Fax: +49-89-2180-76999 E-mail: [log in to unmask] WWW: www.genzentrum.lmu.de *******************************************************