If your translational NCS is defined by a vector that does not correspond to lattice centering, i.e. has numbers different from 0 or 0.5, this is likely a case of order-disorder. Most such cases can be easily diagnosed by abnormal patterns in spot shape, e.g. every second reflection has a non-Bragg streak associated with it. Apparent dense packing, 18% of the solvent, is likely to arise from random packing of molecules in alternative positions within the unit cell, where every second position is occupied. This randomness can be cross-correlated between cells, and this will produce a diffuse scattering. An alternative explanation is that you crystallised a proteolitic fragment of your protein.
Zbyszek Otwinowski > Dear all > i have a small query to ask and seek your suggestions: > > I have collected a data for a protein with 324 residues and processed at > its best in P212121. So Matthews suggest 1 mol in ASU with expected Mol. > weight of 43 kDa with sovent content of 58% and 2 mol./ASU with 18% > solvent > content. However the data suggest possibility of translational NCS so i > think i should ask for two molecules so that both get corrected for NCS. > However for 2 mol./ASU, Matthewssuggests a total mol. weight of 52 kDa. So > how to decide which way to proceed for MR? > > Thanks > Monica > Zbyszek Otwinowski UT Southwestern Medical Center at Dallas 5323 Harry Hines Blvd. Dallas, TX 75390-8816 Tel. 214-645-6385 Fax. 214-645-6353
