April 2015 - phenixbb - phenix-online.org

FINAL REMINDER: Neutrons in Structural Biology
by Meilleur, Flora 06 Apr '15

06 Apr '15

6th Workshop on Neutron Scattering Applications in Structural Biology Oak Ridge, TN. June 1 - June 5, 2015 Application deadline: April 10, 2015 Detailed information can be found on the workshop web page: https://public.ornl.gov/neutrons/conf/gcnb2015. Flora Meilleur, Ph. D Assistant Professor, Molecular and Structural Biochemistry North Carolina State University Neutron Sciences Directorate Oak Ridge National Laboratory Phone: 865-242-5747

1 0

Ensemble refinement
by mohamed noor 04 Apr '15

04 Apr '15

Using the FEM map, I managed to remove more bad waters and add instead ions from the crystallization mix. I tried phenix.ensemble_refinement but the Rfactor increased by 2 % (originally 19/22 % from phenix.refine). Before it crashes at the validation point all the time, it prints out the validation summary with 0.53-3.48 % and 1.87-7.22 % Ramachandran outlier (from 0.3 %, supported by density) and a Molprobity score of 1.57-1.92 and 1.82-2.14 depending on pTLS used (original single model score was 2.08). The clashscore in both settings (pTLS=0.6 and 1) are 0. Do I still go by the Rfactor and decide to not use ensemble refinement at all? Thanks.

3 2

Structure with pseudo-NCS translation
by Mark A Saper 03 Apr '15

03 Apr '15

I know that Phaser takes account of NCS translation in the likelihood statistics ( Read, Adams, McCoy (2013) Intensity statistics in the presence of translational non crystallographic symmetry”). Has this also been incorporated into phenix.refine? I have a structure with pseudo NCS translations because of NCS rotational symmetry. One suggestion that I found in the archives, was to explicitly LS target refinement rather than ML. Any comments? Mark _________________________________ Mark A. Saper, Ph.D. Associate Professor of Biological Chemistry, University of Michigan Ann Arbor MI 48109-1055 U.S.A. saper(a)umich.edu phone (734) 764-3353 fax (734) 764-3323

4 5

refinement
by Almudena Ponce Salvatierra 02 Apr '15

02 Apr '15

Dear all, I am using Phenix.refine after MR and I have a complete model and data to 2.8 Angstrom resolution. However, for some reason, Phenix does not place any water molecules. Is there a setting I could change in order to see whether this situation changes? What could the reason be? Thanks a lot in advance. Best, Almudena -- Almudena Ponce-Salvatierra Macromolecular crystallography and Nucleic acid chemistry Max Planck Institute for Biophysical Chemistry Am Fassberg 11 37077 Göttingen Germany

2 1

twinning
by Shun Liu 01 Apr '15

01 Apr '15

Dear all, Recently I have got a data set that diffracts to 1.7 angstrom. Images look good. During data processing I did not find anything that looks strange. However, when I was doing Phaser-MR, I got a warning: “ Intensity moments suggest significant twinning (>5%). Tests based on possible twin laws will be more definitive.” What does this mean? A twinning data set? I still found a solution and refined the model step by step, using the data (20-1.7 angstrom). It seems that the final model and map are acceptable. But R-factors are 0.24/0.28, very high. Does the twin cause the high R-factors? Is there a solution to detwin? Or are the R-factors acceptable for a twinning data set? Any suggestions are appreciated and thanks in advance! Best, Shun

5 10

a question on henix refine
by Smith Liu 01 Apr '15

01 Apr '15

Dear All, For the Phenix refine, the default for the Scattering table in "other options" in the graphical interface is n_gaussian, in which situation to use electron is much better? And how much would be the benefit to use electron instead of n_gaussian? Smith

2 1

Maps
by mohamed noor 01 Apr '15

01 Apr '15

Dear developers What is the difference between MEM and FEM maps? I read the documentation and my understanding is both are supposed to create beautiful maps :) My problem is I have a structure at 1.9 A (a different protein than the one referred to in my previous question), the Rfactor is around 20/22 %, Rms bonds is 0.03 and Rms angles is 1.845. If the bonds/angles get lower, the Rfactor jumps up (same problem as the other structure). Looking in Coot, there are positive and negative density and missing density for the side chains of residues with high B factor. For some reason, phenix.refine keeps on adding water at strange places even at regions that I suspect to be just noise. For this reason, I want to see if the noise is really noise. A second reason is I have density that seem to be too big for a water molecule but waters were placed anyway, so I want to know if these are real positive density. The dataset was obtained from only 50 degrees, SG is P 61 2 2. Including more images brought up the Rmerge to 30-40% and Rfactor being stuck at 30 %. For some reason, I don't find the X-ray statistics from the phenix.model_vs_data logfile but in essence, I have: 28-1.9: 82 % 6 A - infinity: 95 % in the shells (2.25-2.14, 2.14-2.04, 2.04-1.97, 1.97-1.9) my completeness is around 85-62 % and CCwork is at least 70 % and CC1/2 of the dataset is 60 % at the highest resolution shell. Thanks.

2 1