Dear Charles,
I usually look at the course of CC1/2 (anom) across the resolution bins.
It should be high'ish at low resolution and a good resolution cut-off
for e.g. shelxd is where it drops below 30%.
The certainly by far best criteria is a traced structure (for a protein,
though). With shelx c/d/e that's easy to set up and test. If it cannot
be traced, this does not mean there is no useful anomalous signal, but
that's also true for all the other indicators - there are structures
being solved from anomalous data where the usual indicators indicate
hardly any signal at all.
E.g. the anomalous data available for 3LDC looks pretty hopeless:
Resl. Inf. 7.77 4.78 3.60 2.94 2.52 2.22 1.99 1.81 1.67
<d"/sig> 1.10 0.95 0.84 1.01 0.99 0.95 0.83 0.73 0.71 0.66
yet, shelxd locates three out of 5 K+ ions (with lambda = 0.979A...)
within only 100 trials and no special settings.
Best,
Tim
On 09/04/2014 10:05 PM, CPMAS Chen wrote:
> Dear All CCP4 users,
>
> Recently, I have protein crystals cocrytallized with Br-containing ligand.
> sometimes, I feel confusion about whether the data have reliable anomalous
> information or not.
>
> Do you guys have some recommendation of the criteria? phenix reported
> anomalous measurability, CCP4/aimless has RCRanom. Sometimes, they are not
> consistent.
>
> Thanks!
>
> Charles
>
--
Dr Tim Gruene
Institut fuer anorganische Chemie
Tammannstr. 4
D-37077 Goettingen
GPG Key ID = A46BEE1A
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