Hi Lei Fang, I cannot tell what technique you are using for crystallization. Also, many details like protein concentration, temperature of crystallization etc. are missing in your email so it's hard to guess what's going on.
In any case, here are my thoughts. I used to get a shower of needles from hanging drops at 19C but a lot fewer and bigger crystals when I set up sitting drops under mineral oil at 19C. The crystals took lot longer to grow (two weeks as opposed to four days using hanging drop) so bear that in mind. My guess is that you may be able to find protocols if you just do a quick web search. There are many other ways to optimize crystal growth and size including playing with temperature of crystallization (lowering to 4C), amount of precipitant vs protein, drop size, crystallization technique, seeding by dilution etc. Hope that helps. Raji On Mon, Feb 25, 2013 at 11:02 AM, lei feng <spartanfeng...@hotmail.com>wrote: > Hello everyone, > I need your suggestion for slowing down crystallization for my protein > my protein got hit in PEG/ION #5 ( 0.2 M MgCl2, 20% PEG 3350, pH 5.9), but > it crystallize too fast. In 1 hr I can see tons of tiny needles. > Can anyone give me some suggestion on how to slow down the process? I used > lower conc. of potein, lower conc. of PEG ( 10%), it helped a little bit, > giving me small rod crystal. but no improvement after that. > > Thank you very much for your suggestions > > > -- Raji Edayathumangalam Instructor in Neurology, Harvard Medical School Research Associate, Brigham and Women's Hospital Visiting Research Scholar, Brandeis University
