Assuming that the MR solution is correct (I agree with Eleanor, that you need to be certain about your selection of space group), then use your complete model of chain A superimposed on chains B, C, and D. Then refine and build the heck out of it. In a similar situation, it was relatively easy for me to find two out of three molecules by MR. We were never really convinced that there was a third (Matthews coefficient dicey, suggesting either 2 or 3). After substantial refinement and building, the third chain was apparent, and we rebuilt it completely. Looking at the average B-factors of each chain, and the overall packing environment, chain A was tight, chain B looser, and chain C will substantially fewer contacts.
Bernie Santarsiero On Tue, February 13, 2007 10:07 am, Eleanor Dodson wrote: > Sometimes this sort of disorder is due to an error , so the first thing > is to check very carefully that the solution makes sense. > > Why are you so sure there are 6 copies in the asymmetric unit? > > In situations like this I first worry about SG. > > Is there a pseudo-translation vector? This can make it hard to decide on > the SG.. > > Is there an alternate spacegroup with fewer molecules in the asymm unit? > > What does the self rotation show? > > > > Yanming Zhang wrote: >> Dear All, >> >> Maybe this is a trivial question: >> >> My data should have 6 molecules in one assymetric unit. MR could find >> out 4 molecules. After this, no matter how hard I have tried, no more >> molecules can be found. At this stage, I suppose that all other copies >> are dis-ordered. And go ahead to do refinement with 4 molecules (ABCD) >> available. >> The density for A is quite good. But for BCD are very dis-ordered. >> Many breaks in chains. I'd like to ask you: >> In a situation like this, should I: >> A, Use NCS for all copies? >> B Do not use NCS at all? >> C, Use NCS just for BCD? (even dis-ordered, but similar)? >> What is the trick to lower down Rfree as soon as possible, if you have >> experienced the same situation before? >> >> >> Thanks >> >> Yanming >> >> >
