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Hi, This is a non-CCP4 question, but I hope to receive some comments and guidance from the bb members: SDS-PAGE analysis on multiple small crystals (~30x30x30 microns) possibly indicates the presence of 3 species: intact target and two other bands that could be degraded portion of the target or impurities from the purification. Both native and SeMet data have been collected on these crystals (3.2-3.4A) which take 15-60 days to appear/grow. They belong to R32 space group with cell dimensions of ~145x145x515 A. Data can be processed without any trouble and Rsyms are ~3-5% in lowest shell, 10-13% overall (for the native). Diffraction spots are good. Most of the data sets collected do not indicate twinning. 1) If there are multiple proteins in the crystal, are they likely to be in a "complex"? OR 2) Can the individual species have different compositions in different regions of the crystal, i.e., they are not really a "complex" but are present in one asu and not in another (Is that possible,since by definition, the asu should be the repeating unit and thus have to be of unique composition)? If that were the case, would such small crystals still diffract reasonably well? If it is most likely to be case (1), I suppose the structure of this "complex" can be solved in order to get the structure of the actual target, but it may not be possible to solve if it is case (2). I would appreciate any comments or pointers to related/similar reports in the literature or from anecdotal evidence. Thanks, Debanu.
