Afshan Radaev and Sun published a paper a few years ago showing that crystallization conditions for complexes are strongly biased towards PEG conditions (rather than e.g. high salt conditions). The reference is below.
I would use microseeding into random screens [2], using the crystals that you have as seed crystals. Ideally you should find conditions where *both the complex and the seed stock are stable*. By coincidence we had a paper accepted this week by Crystal Growth and Design on this exact topic, see below. Best wishes Patrick ______________________ [1] Radaev, S; Sun, P.D. J. Appl. Crystallogr. 2002, 35, 674-676. [2] D'Arcy, A.; Villard, F.; Marsh, M. Acta Crystallogr. 2007, D63, 550-554. [3] Patrick D. Shaw Stewart , Stefan A. Kolek , Richard A. Briggs , Naomi E. Chayen , and Peter Baldock Cryst. Growth Des., Just Accepted Manuscript. "Random microseeding: a theoretical and practical exploration of seed stability and seeding techniques for successful protein crystallization". http://pubs.acs.org/doi/abs/10.1021/cg2001442 On Fri, May 27, 2011 at 1:24 PM, Afshan Begum <[email protected]> wrote: > Dear All, > > I have a severe prob lam to performed my ligand binding study with > corresponding protein. I have taking the native diffraction data at 1.75 A > and after that i have performed soaking as well co-crystallization > experiment with my inhibitors. > Problem is that at the active site phosphate ion always bind instead of > inhibitors. I have used 1.6 M ammonium phosphate conc at the > crystallization recipe which is a very weak inhibitor of my protein whereas > the ligand is already clinically applicable but due to the very high conc. > of phosphate i have not achieved my target. If some one can suggest me what > else i can replace with ammonium phosphate or any other suggestions would be > appreciated. > > I have tried to grown crystals some other condition but the crystal was not > diffracted beyond 3.5 A. > > Best Regards > > AFSHAN > -- [email protected] Douglas Instruments Ltd. DouglasHouse, EastGarston, Hungerford, Berkshire, RG177HD, UK Directors: Peter Baldock, Patrick Shaw Stewart http://www.douglas.co.uk Tel: 44 (0) 148-864-9090 US toll-free 1-877-225-2034 Regd. England 2177994, VAT Reg. GB 480 7371 36
