Several years ago I solved a small RNA structure by direct methods using the CCP4 program ACORN, and built the model using Nautilus. This was with data to only 1.25 Å resolution, collected at the Se edge, so there was no significant anomalous signal.
I think that this worked like a charm because the crystal probably diffracted to around 1 Å resolution, but due to beam line hardware issues, I decided it wasn’t worth it to try to collect the higher resolution data. Diana ************************************************** Diana R. Tomchick Professor Departments of Biophysics and Biochemistry University of Texas Southwestern Medical Center 5323 Harry Hines Blvd. Rm. ND10.214A Dallas, TX 75390-8816 diana.tomch...@utsouthwestern.edu (214) 645-6383 (phone) (214) 645-6353 (fax) On Apr 20, 2018, at 2:35 PM, Randy Read <rj...@cam.ac.uk> wrote: I think that starting with a direct methods program like shelxt would be fun. If that doesn’t work, it could be interesting to try to solve it by molecular replacement with fragments varying from a tetraplex, a base pair or even just single bases. (Assuming that Phoebe’s concern about twinning does not turn out to be correct…) Best wishes, Randy Read ----- Randy J. Read Department of Haematology, University of Cambridge Cambridge Institute for Medical Research Tel: +44 1223 336500 Wellcome Trust/MRC Building Fax: +44 1223 336827 Hills Road E-mail: rj...@cam.ac.uk Cambridge CB2 0XY, U.K. www-structmed.cimr.cam.ac.uk > On 20 Apr 2018, at 20:09, Tim Gruene <tim.gru...@psi.ch> wrote: > > Dear Rafal, > > shelxt does not require the space group, it only needs the Laue group. If it > finds a decent solution, it'll find also the space group for you. > > Best, > Tim > > On Friday, April 20, 2018 3:30:36 PM CEST Rafal Dolot wrote: >> Dear CCP4BB, >> >> I've recently collected data for 11mer build of DNA (9xG, 2xT). XDS, and >> DIALS gave me similar solution - SG: I2(1)2(1)2(1) or I222, with cell >> dimension 20.65, 22.96, 43.37, 90, 90, 90, what is too small for this >> size of the molecule. 11mer is rich in G, so we expect the G-tetraplex >> formation. Data were collected to almost 1 A, so it should be enough for >> trials with direct methods/ab initio solution. What I should do first to >> find correct SG and/or cell parameters? >> >> Best regards, >> >> Rafal > > -- > -- > Paul Scherrer Institut > Tim Gruene > - persoenlich - > OSUA/204 > CH-5232 Villigen PSI > phone: +41 (0)56 310 5297 > > GPG Key ID = A46BEE1A ________________________________ UT Southwestern Medical Center The future of medicine, today.
