Dear Alex, We’ve had very good luck using Phaser to place large numbers of copies of good models. It’s in this kind of case where the increased sensitivity of the likelihood approach really helps. I would suggest trying the different choices of model as alternatives, and you might also want to make an ensemble in which loops that deviate among the different models have been trimmed off.
If you need more advice on how to do this, you can get in touch off-line. 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 31 Oct 2016, at 18:16, Alex Lee <alexlee198...@gmail.com> wrote: > > Hi All, > > I have a protein which contains 72 amino acids. The crystal of this protein > diffracts to 2.5A with SG P31 (CELL Dimension 65.9590 65.9590 164.3900 > 90.0000 90.0000 120.0000). Pointless indicates no twinning. > > Mathew coefficient as below: > For estimated molecular weight 7919. > Nmol/asym Matthews Coeff %solvent P(2.49) P(tot) > _____________________________________________________________ > 1 26.07 95.29 0.00 0.00 > 2 13.04 90.57 0.00 0.00 > 3 8.69 85.86 0.00 0.00 > 4 6.52 81.14 0.00 0.00 > 5 5.21 76.43 0.00 0.00 > 6 4.35 71.71 0.00 0.01 > 7 3.72 67.00 0.02 0.02 > 8 3.26 62.28 0.05 0.05 > 9 2.90 57.57 0.11 0.11 > 10 2.61 52.85 0.19 0.19 > 11 2.37 48.14 0.25 0.25 > 12 2.17 43.42 0.22 0.22 > 13 2.01 38.71 0.11 0.12 > 14 1.86 33.99 0.03 0.03 > 15 1.74 29.28 0.00 0.00 > 16 1.63 24.56 0.00 0.00 > 17 1.53 19.85 0.00 0.00 > 18 1.45 15.13 0.00 0.00 > 19 1.37 10.42 0.00 0.00 > 20 1.30 5.70 0.00 0.00 > 21 1.24 0.99 0.00 0.00 > _____________________________________________________________ > > I have at least 10 structures in PDB with homology 60% or above. > I tried the CCP4online MrBump and Balbes for automatic molecular replacement. > No solutions at all. > I do not know if this is because that the high number of copies in ASU (maybe > 10 copies as shown by Mathew coefficient) hamper the MrBump and Balbes to do > MR? > > Dose anyone experience similar difficulties with high number of copies to do > automatic MR? > > Thanks ahead!
