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 41 rue Jules Horowitz F-38027 Grenoble Cedex 01 Tel: +33 438789605 Fax: +33 438785494
