You don't mention any quality indicators on your derivatives, nor
resolution.
Presuming they actually have some decent phasing power, you may be able
to generate phases & maps using SIR phasing + solvent flattening. If you
can do that for each isomorphous set, then you could combine them using
multiple space group noncrystallographic averaging.
Or, if the derivatives contain atoms with anomalous scattering, you
could solve a derivative alone with SAD methods, or a derivative +
native set with SIRAS. Once you get crude maps, you can once again try
to combine the two sets with multiple space group averaging.
As for MR, there are lots of things you can try. Once again, you have
provided no detail on what the sequence similarity is, or any other
factor that would allow us to judge the likelihood of success.
You could search again with the model clipped down to poly-Ala. You
could search again with any external loops trimmed off. If it is a
multiple domain molecule, you could search individually with single
domains. You could find additional search models, and search with a
suite rather than single model. MR programs will suck up as much free
time as you can provide them.
On 11/18/14 15:01, joy yang wrote:
Hi All,
I have two derivative datasets (heavy atom A and B) and two native
datasets (a and b), A and a are isomorphous, B and b are isomorphous,
however, a and b (or A and B) are not isomorphous.
I was able to make two difference patterson maps (FA-Fa and FB-Fb) and
search for heavy atoms against them, the possible positions of heavy
atom A and B are very close to each other in the unit cell (which
seems to me that I am very close to a right phase, though not there
yet), I am wondering if there is any means for me to combine the
information from FA-Fa and FB-Fb as the two native datasets are not
isomorphous? And also, I have a homology model which I tried molecular
replacement and failed, is there any means for me to combine the
information from the model too?
Best,
Bei
--
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All Things Serve the Beam
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David J. Schuller
modern man in a post-modern world
MacCHESS, Cornell University
schul...@cornell.edu
