Hi -- I have a high resolution structure (1.6 A) where I'm ready to
deposit except I have
some very strange density, shown in the two pictures here -- sort of a
sphere with a
split cresent around it, falling between molecule A and B His 138
imidazole rings. The
sphere is modeled as a Cl atom, more for "kicks" because resulting
2Fo-Fc maps still have
considerable positive difference density throughout the sphere. There
are 4 molecules in
the AU, the imidazole ring of H138 in molecules C and D point into a
solvent channel.
Crystallization conditions are 0.2M Mg Chloride, 0.1M Bis-Tris pH6.5,
25% PEG3350,
cocrystallized in 2.5mM Glycero-3Phosphocholine and cryoprotected by
dipping in
Paratone_N oil.
Let me know what you're thoughts are and thank you for your help.
Alex Singer
--
Dr. Alex Singer
C.H. Best Institute
112 College St. Room 70
University of Toronto
Toronto, Canada, M5G 1L6
416-978-4033
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