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Geny, Unfortunately, it is a very common case. In our practice, we have 20-40% of protein crystals that show this kind of diffraction. We still call them crystals because they often look beautiful, with nice edges and planes. My understanding is that the protein molecules are not arranged orderly enough to show diffraction spots. It is possible that the crystal was destroyed when the cryo protectant was added. You may try RT as suggested by Roger (which is the ultimate test), or just try other methods of cryoprotection and/or cryoprotectants. For some ideas, i suggest looking into the paper "A review of techniques for maximizing diffraction from a protein crystal in stilla" by Janet Newman. Shooting it a better X-ray source is unlikely to improve the picture significantly in my opinion. You may simply try increasing the radiation dose many folds to see if there are diffraction spots at all. Good luck! With best regards, Ivan Shabalin, Ph.D. Research Scientist, Department of Molecular Physiology and Biological Physics, University of Virginia, 1340 Jefferson Park Avenue, Pinn Hall,Room 4223, Charlottesville, VA 22908 ----