MULITSCALE manual; anisotropic scaling + solvent
puius at aecom.yu.edu
Thu Feb 27 11:07:38 EST 1997
Does anyone out there (perhaps someone from Dr. Brunger's group?)
have the manual for the MULTISCALE keyword in X-PLOR 3.851?
Perhaps there's already a script out there to do what I'm interested
in, which is this:
I have data that is fairly anisotropic (I brought down my Rfree by
4% by applying overall anisotropic B-factors!) which seems to
refine best with a solvent model. I am quite aware that one of
my options is do drop the solvent model, but it seems to help quite
a bit -- when I apply both, I get very reasonable R-factors.
The problem is, each run I get different refinements for the
anisotropic Bs and the solvent, which can result in huge isotropic B
all around (even through the R-factors stay low). I've been trying to
use multiscale to simultaneously fit an ISOTROPIC solvent model and
and ANISOTROPIC Fobs scale; this is apparently impossible. And I
don't want to fit an anisotropic solvent model!
So, my questions are:
1) DOes anyone have a manual for the MULTISCALE keyword?
2) Does anyone have a tested routine that fits a solvent model
and anisotropic B-factors?
3) Am I nuts in refining the Bij factors each time? Should I
only do it once? (I have maybe 5-10% more atoms to add to the model,
and was assuming that it will affect the numbers)
Now, I realize that whatever isotropic B-factors I refine (this is
a 1.9A structure, so it's justified) would be on top of the
anisotropic ones. So if my B11,B22,B33 are, say 5, 10, and 20, I
can absorb some of that into my isotropic factors to get something
close to 0, 5, and 15 (I _know_ it doesn't work that way, but you
get the idea).
Which brings me to my last question:
4) Can I tweak my overall B-factors so that my smallest Bij is
close to zero, and then keep those Bij coefficients?
Thanks in advance to any replies to this wandering and wordy
Yoram A. Puius Albert Einstein College of Medicine
mailto:puius at aecom.yu.edu Department of Biochemistry
5th year M.D.-Ph.D. 1300 Morris Park Avenue, Bronx, NY 10461
More information about the X-plor