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Dear CCP4 members, I am working on a structure of a protein in complex with an antibody fragment (approx. 50kDa together). Molecular replacement with closely related proteins always comes up with one complex in the asymmetric unit, although MW of protein to which Matthews applies is 125kDa and corresponds to two complexes. Phaser gives two warnings: Large non-origin Patterson peak indicates that translational NCS is present. Solutions with Z-scores greater than 27.2 (the threshold indicating a definite solution) were rejected for failing packing test I couldn’t get a solution with two subunits although I have tried multiple combinations including only conserved parts of both proteins and different space groups including P1. Phenix Autobuild also yielded only one complex. So, the question is whether I can use that structure as is despite very high solvent content (80%) or should I try smth else. I would be very grateful for any suggestions. When the solution with a single complex is refined the statistics are the following: R-work 0.2129 R-free 0.2459 Matthews Coefficient: 6.22 Percentage Solvent: 80.22 Resolution range (Å) 48.34 - 2.9 (2.98 - 2.9) Space group P 62 2 2 Unit cell 167.45 167.45 143.538 90 90 120 Multiplicity 19.1 (18.3) Completeness (%) 99.44 (94.39) Mean I/sigma(I) 24.59 (2.71) Wilson B-factor 64.28 R-merge 0.1256 (1.186) R-meas 0.1291 CC1/2 0.999 (0.85) CC* 1 (0.959) Thank you very much for your help, Anna Dr. Anna Koromyslova, Postdoctoral researcher German Cancer Research Center (DKFZ), F150 Im Neuenheimer Feld 242 D-69120 Heidelberg Germany