Hello,
I think this depends on the type of problem you are facing:
if the 2 crystals are not isomorphous then you cannot have the same
R-free sets;
if the 2 crystals are isomorphous then either you do not worry about
keeping the same R-free set (but then the starting structure must be
"perturbed enough" to get rid of R-free bias during refinement), or you
keep the same indices for the reflections in the 2 R-free sets ("same
reflections" in your message) in which case there is no R-free bias at
the beginning of refinement.
By R-free bias I mean this: in your "new" (liganded) crystal form, there
are reflections that "have seen the Fo's" during refinement of the
native structure but that are in the R-free set in the ligand structure.
This leads to bias.
HTH,
Fred.
On 28/02/13 06:54, Kavyashree Manjunath wrote:
> Dear users,
>
> Is it mandatory to use the same reflections for
> Rfree calculations of a ligand bound data as that
> of its native?
>
> Thank you
> With Regards
> Kavya
>
--
Fred. Vellieux (B.Sc., Ph.D., hdr)
IBS / ELMA
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