ni hao,
> I have a question about how to improve the electron density. I have two
> indepedent molecules in the asymmetric unit (1.9 A resolution). I solved the
> structure with PHASER and refined with CCP4i (Rfree = 0.29).
>
> For the first molecule, the density is very good, but for the second one,
> the density is much worse than the first one. Are there any ways to improve
> the density of the second molecule, such as some kinds of averaging? Why
> that happens?
there can be various causes for this such as undetected twinning or a
spacegroup error. if you can exclude those possibilities, it could also be
that the weak-density molecule has fewer packing interactions and thus is less
well ordered, and therefore has a higher overall temperature factor. you can
investigate this with SPANCSI (http://xray.bmc.uu.se/usf/spancsi_man.html#H5).
--dvd
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Gerard J. Kleywegt
[Research Fellow of the Royal Swedish Academy of Sciences]
Dept. of Cell & Molecular Biology University of Uppsala
Biomedical Centre Box 596
SE-751 24 Uppsala SWEDEN
http://xray.bmc.uu.se/gerard/ mailto:[log in to unmask]
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