jiang at LAPLACE.CSB.YALE.EDU
Thu Dec 7 22:51:21 EST 1995
> We have been having trouble with our B's. In some structures we have an average B of
> ~30, other structures, same protein and data collection/reduction routine, have an average
> B of ~10. The electron density does not appear to be that much different between these
> structures. Our data are collected to 2.5A resolution. We are, of course, using XPLOR
> for refinement. Has anyone experienced this before? If so how did you get the situation
> resolved? Thanks.
It is probably that the overall B scale was set too high/low.
1. Check with the Wilson plot by using the same resolution range
that was used in the B refinement. The determined B scale from
Wilson plot would be comparable with the overall average
B value. If there is big differences between two Bs,
you can reset all B values to the B_Wilson scale and
re-carry out the B refinement again in X-PLOR.
2. If there is also a big difference on Wilson B values
between different structures, and same data correction/
reduction routine are used, It may be a meaningful
difference! It is normal that average B values are around 10-30
for macromolecular structures. Usually, the lower resolution
data the higher average B value.
3. Check with data completeness. Missing data in the
high resolution range could also lead to an artificial average
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