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Hello Everyone
I'll post a summary after I've waded through the (many) answers, but I
seem to have left out some information. There are some interesting
suggestions.
I've already checked enantiomorphic, and all the other P6x22 and P6x
space groups. Only P6122 gives a good MR solution (well, so does P61,
P31, P312, but these MR solutions have the same packing as P6122. MR
solutions in lower symmetry space groups with fewer molecules/AU have
low Z-scores, and high R (when I try to refine it), and maps that tell
me to add more molecules.) (I've also gone as low in symmetry as P31
(etc) without any improvement in the situation. Heck, I've gone to
orthorhombic symmetry too.) After the MR solution in P6122, I could see
clear density for helices and side chains that were not in the model
structure. (I really like phaser because it gives maps.)
The model I used is only about 60% of my protein, consequently, the MR
solution has no packing problems. It is in building the remaining part
of the structure than I run into the problem. R/Rf are 0.27 / 0.33 for
2.3 A data. At this point, there is nothing more to build, the maps are
flat. I have no information as to what the structure of those 30
residues are - they're not in the model structure I used. Since some of
these are implicated as catalytically important residues, I'd really
like to see them. (I know, grow crystals under different conditions).
Interestingly, if I download the structure factors for the structure I
used for the MR (a thanks in general to all who deposit structure
factors), the structure I used as a model seems to have the same
problem. A big chunk of the protein is missing and the molecule runs
into itself across a two-fold (it's a different cell and space group).
Sue
