How non-isomorhous is non-isomorphous? Can you give the cells and putative Spacegroups for A a B & b?
You can often get information at low resolution for this sort of problem if there is some level of similarity. Eleanor On 18 November 2014 21:15, David Schuller <[email protected]> wrote: > 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 > > > > -- > ======================================================================= > All Things Serve the Beam > ======================================================================= > David J. Schuller > modern man in a post-modern world > MacCHESS, Cornell University > [email protected] > >
