Hello everyone, I am trying to crystallize the truncated version of a memebrane protein (30 amino acids truncated, including signal sequence a transmembrane helix). The protein expresses in inclusion bodies and I solubilize it in 8 M urea and finally purify it in 20mM Tris, 50mM- 300mM NaCl, 5% glycerol, pH 8.5. I have been able to gow crystals but all of them grow as thin plates. The best resltion obtained so far is 3.7 A. Moreover, for SAD phasing using the natural Sulpurs, the Cr beam gives a maxmum resoltion of 7 A. I have exhausted all screens in my lab and set up expansions of all positive hits, but all I get are plate like crystals with poor resoltion.
Can anyone suggest how to improve my crystals? Moreover, is the data I am getting so far workable for SAD phasing? mY protein is 500 amino acids long with 11 Methionines, spread out almost through out the protein length. Eagerly awaiting some help! Thanks ! -- Nazia Nasir PhD Scholar Protein Crystallography Lab National Institute of Immunology New Delhi
