Dear Linda, If your molecule is not very big, your cell is not very big, you have an approach to modern in-house X-ray facility, your crystal diffract reasonably well ( :-\ ) you can try S phasing. If you will be able to measure accurate data, S anomalous phasing at 1.5417 Angstrom of Cu radiation may work like charm (it is usually a case in my hands). In addition, if it happened that you have also couple of Cl etc. it will support phasing even more. I prefer to test S-SAD cases with shelxC/D/E pipeline under HKL2MAP GUI. Happy holidays FF Dr Felix Frolow Professor of Structural Biology and Biotechnology, Department of Molecular Microbiology and Biotechnology Tel Aviv University 69978, Israel
Acta Crystallographica F, co-editor e-mail: mbfro...@post.tau.ac.il Tel: ++972-3640-8723 Fax: ++972-3640-9407 Cellular: 0547 459 608 On Dec 26, 2012, at 20:33 , Linda Olson <lol...@mcw.edu> wrote: > Dear All, > > I have read a recent paper by Salgado et al about using non-auxotrophic > E.coli to incorporate SeCys into recombinant protein for phasing purposes. > Does anyone have a source for Selenocysteine? I have also seen a paper by > Schaefer et al which uses nitric acid treated elemental Se for a sulfur > surrogate to generate Se-labeled protein. Has anyone else tried this? My > proteins are rich in Cys and tend to lack Met so the prospect of labeling cys > is very attractive. > > Thanks, > > Linda > ________________________ > Linda Olson, PhD > Research Scientist II > Dept Biochemistry > Medical College of Wisconsin > 8701 Watertown Plank Rd > Milwaukee, WI 53226 > > phone: 414-955-8545 > fax: 414-456-6510 > _________________________
