Dear Tim, Thank you Sir. I have a data which was collected after cocrystallization. We already have the structure for the apo form and there is absolutely no difference in the sequence. Other crystal structures solved by soaking methods, I used to get FOM of around 0.7 by the end of first refinement. So I was little skeptical as to why the FOM is low for the present data (0.57 at the end of first refinement.)
The data was 3.3 Ang, P21 (with a 17.2% pseudo-translation peak at 0.399 0.0 0.015). Density fairly fits, as seen after first round of refinement. So is there any relation between the presence of pseudo-translation and FOm being low. I was of the impression that as the solution from the apo structure is already known, there might not be much error in the phases ie, FOM. Kindly clarify this point. I have not used direct methods, but I assumed that the FOM for the initial phases obtained would be lower which has to be improved. Please correct me if I am wrong. Thank you Regards Kavya > Dear Kavya, > > I am not sure the term 'figure of merit' is defined in absolute terms. The > best criterion for a solved structure after MR is an electron density of > such > a high quality that you can start model building to extend the molecule > and > eventually end of with a refined model. > > Direct methods usually don't solve your protein structure, they solve the > substructure. From their you normally have to apply density modification > in > order to get to an interpretable (extensible) density map. > > Best regards, > Tim > > > On Monday, November 07, 2016 02:31:39 PM Kavyashree Manjunath wrote: >> Dear users, >> >> What is the acceptable values for the figure of merit (FOM) >> for an MR solution (where the model is atleast 99% identical). >> what is it in case of solution from direct methods? >> >> Thank you >> Regards >> Kavya >> >> >> -- >> This message has been scanned for viruses and >> dangerous content by MailScanner, and is >> believed to be clean. > -- > -- > Paul Scherrer Institut > Dr. Tim Gruene > - persoenlich - > Principal Investigator > Biology and Chemistry > OFLC/102 > CH-5232 Villigen PSI > > Phone: +41 (0)56 310 5297 > > GPG Key ID = A46BEE1A > >
