structural refinement using low temperature data
s_aarono at EDUSERV.ITS.UNIMELB.EDU.AU
Wed Apr 10 19:54:30 EST 1996
> Does anyone has experience of structural refinement using low
> temperature data? I try to refine my protein structure with low temperature
> data, but the r value is about 0.3, which can't go down further without B-value
Low temperature structures often have lower B-factors than the equivalent
structures refined against room-temp. data.
If you are at R=30%, then you could try doing some B factor refinement.
(Individual restrained, or Group, depending on the resolution of your data)
If you don't want to do group or individual B factor refinement yet, you
could try refining a single B factor for the entire structure. (using
the group protocol with group=(not hydrogen) )
Also, if you suspect that the data is anisotropic, try compensating
for this by refining an overall anisotropic temperature factor
(which will be applied to the HKL's, not your structure), using the
I have found that there are no special problems associated with refining
against low temperature data. Of course, you should use Rfree in all
cases to see if you are over-fitting.
Hope this helps,
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