Re: [ccp4bb] off-topic: negative thermal shift upon ligand binding

2017-07-08 Thread Nicholas Larsen
In theory, what you say is quite sensible. But there is one interesting counter example I am aware of.The fragment tool compound that eventually gave rise to the clinical compound indeglitazar ( http://www.pnas.org/content/106/1/262.full.pdf) gives a negative shift by DSF (in our hands): [imag

Re: [ccp4bb] off-topic: negative thermal shift upon ligand binding

2017-07-08 Thread Bonsor, Daniel
What are you using to dissolve the compounds? If DMSO or other organics, you maybe witnessing unfolding due to the organics. Have you done a control of just the solution with the protein. Some compounds may drastically change the pH of the buffer your protein is in. You maybe observing a change

[ccp4bb] off-topic: negative thermal shift upon ligand binding

2017-07-08 Thread megha abbey
Hello, I am working on DSF to verify if some compounds bind to my protein. I see a negative shift of about 3-4 degrees upon ligand addition (dose-response) in comparison to the protein alone. I assume that this might be due to the binding of compound to the unfolded stated rather than folded prote

[ccp4bb] Arcimboldo, ShelxE, Windows

2017-07-08 Thread Bonsor, Daniel
Dear All, Does Arcimboldo actually run on WIndows as I can see it is installed and so is ShelxE, but I have a warning in the GUI saying "ShelxE is not found and option to run on 'this machine' is disabled. Is this a bug, do I need alter something so get it to recognize ShelxE or it does not ru

Re: [ccp4bb] Rmergicide Through Programming

2017-07-08 Thread Edward A. Berry
But R-merge is not really narrower as a fraction of the mean value- it just gets smaller proportionantly as all the numbers get smaller: RMSD of .0043 for R-meas multiplied by factor of 0.022/.027 gives 0.0035 which is the RMSD for Rmerge. The same was true in the previous example. You could mu

Re: [ccp4bb] Rmergicide Through Programming

2017-07-08 Thread James Holton
The expected distribution of Rmeas values is still wider than that of Rmerge for data with I/sigma=30 and average multiplicity=2.0. Graph attached. I expect that anytime you incorporate more than one source of information you run the risk of a noisier statistic because every source of infor

Re: [ccp4bb] Rmergicide Through Programming

2017-07-08 Thread Frank von Delft
It is quite easy to end up with low multiplicities in the low resolution shell, especially for low symmetry and fast-decaying crystals. It is this scenario where Rmerge (lowres) is more misleading than Reas. phx On 08/07/2017 17:31, James Holton wrote: What does Rmeas tell us that Rmerge does

Re: [ccp4bb] Rmergicide Through Programming

2017-07-08 Thread James Holton
What does Rmeas tell us that Rmerge doesn't? Given that we know the multiplicity? -James Holton MAD Scientist On 7/8/2017 9:15 AM, Frank von Delft wrote: Anyway, back to reality: does anybody still use R statistics to evaluate anything other than /strong/ data? Certainly I never look at

Re: [ccp4bb] Rmergicide Through Programming

2017-07-08 Thread Frank von Delft
Anyway, back to reality: does anybody still use R statistics to evaluate anything other than /strong/ data? Certainly I never look at it except for the low-resolution bin (or strongest reflections). Specifically, a "2%-dataset" in that bin is probably healthy, while a "9%-dataset" probably H

[ccp4bb] Postdoc position at SGC Univ of Oxford, on structural biology of meganucleases

2017-07-08 Thread Wyatt W. Yue
Dear all We are recruiting a Postdoctoral Scientist, with experience in structural biology of protein-nucleic acid complexes, to join the research group led by Associate Professor Wyatt Yue at the Structural Genomics Consortium (SGC), University of Oxford. In collaboration with Precision Bioscien

Re: [ccp4bb] Rmergicide Through Programming

2017-07-08 Thread James Holton
Sorry for the confusion. I was going for brevity! And failed. I know that the multiplicity correction is applied on a per-hkl basis in the calculation of Rmeas. However, the average multiplicity over the whole calculation is most likely not an integer. Some hkls may be observed twice while