What does the matthews_coeff indicate? You would expect more water than
that, but maybe you have a low Matthews_coeff indicating little solvent?
maybe you have lost the low resolution data which makes it harder to
find water? Maybe you have refined with bulk solvent scaling -
sometimes that also masks the water and you have to look at lower sigma
levels.
Your strong Fo-Fc peak might indicate a rogue bit of data..
Eleanor
Sabini, Elisabetta wrote:
> Dear all,
>
> what does it mean when a structure doesn't have many water molecules?
>
> I have a 2.3A data set, 2 molecules in the AU (260 residues each), space
> group C2221 - I haven't finished my water search but I don't seem to have
> more than 20-30 obvious/good water molecules. The Rfac/Rfree are 22/30%,
> the protein is modeled and the ligands are in.
>
>
> I collected the data at APS SERCAT ID-22. Did I have a dry crystal (!!) or
> did the beamline dried it up?!
>
> How many water molecules should I expect at this resolution?
>
> Also, what does it mean when a strong peak in the Fobs-Fc doesn't have the
> corresponding 2Fobs-Fc map covering it even at very low sigma?
>
> Thank you!
>
> Eli :o)
>
> PS: I have attached the statistics for the data set from XDS
>
>
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