Hello Lande, the map which you have fitted looks quite good, as does the diffraction pattern. At that resolution it will benefit from anisotropic refinement, I think. What sort of R-and R-free do you have? You mentioned they are high with some of your solutions. What does the solvent content suggest for the number of molecules per asymmetric unit and have you found them all? With MR, there is usually a bewildering array of peaks with the same height, due to the high symmetry of the translation function. The programs will sort that out for you, usually. Is that what you mean with 48 solutions? Are you sure of the space group? The main MR progs can try all possibilities, I think, so I assume you have done this. Also, my first and most memorable encounter with tNCS was with a crystal which had an NCS 2-fold parallel with a crystallographic 2(1) screw-axis. To my mind tNCS is just rotational NCS with a screw translation? Others will probably disagree ;-0
Best wishes, Jon Cooper. jon.b.coo...@protonmail.com Sent from Proton Mail mobile -------- Original Message -------- On 18 Jul 2023, 10:06, Lande wrote: > How to deal with tNCS? Dear all, I have read topics talking about tNCS > problem a few years ago and have faced many tNCS data during my work. > Generally, I just turned that tNCS button on in phaser during MR, and ignored > high R/R-free if the MR solutions were correct. However, I always thought > about what made tNCS to occur and what I can do further on tNCS data. > Recently, I got sub 1.5A diffraction data of a simple protein (~100 amino > acid) soaking with a large ligand and it seems it suffers severe tNCS. It is > very clear that two of its unit cell axis are doubled and there is many ghost > density around the model. The other 10 datasets with different soaking time > and concentration do not have tNCS, No ligand in there after modeling. So all > my hope lays on that tNCS one. Here are my questions: 1. I know some proteins > tend to form tNCS crystal but what causes tNCS in this crystal only? 2. In MR > 48 solution were found and currently I have 4 copies in ASU. There seems to > be more to fit the empty density. The map is messy and I cannot determinate > the ligand status. What can I do now? Here I linked some screenshots. Any > suggestions or articles to read will be helpful. Regards, Lande Fu > > --------------------------------------------------------------- > > To unsubscribe from the CCP4BB list, click the following link: > https://www.jiscmail.ac.uk/cgi-bin/WA-JISC.exe?SUBED1=CCP4BB&A=1 ######################################################################## To unsubscribe from the CCP4BB list, click the following link: https://www.jiscmail.ac.uk/cgi-bin/WA-JISC.exe?SUBED1=CCP4BB&A=1 This message was issued to members of www.jiscmail.ac.uk/CCP4BB, a mailing list hosted by www.jiscmail.ac.uk, terms & conditions are available at https://www.jiscmail.ac.uk/policyandsecurity/
