Hi Rhys, I suspect that what you call a gel might be phase separation (correct me if this is wrong) like an oily phase enriched in protein and detergent. you may have too much detergent in your drop. may I ask what detergent you are using (low or high CMC) and at what concentration of detergent do you think you are when you setup your drops. you might have concentrated more detergent than you think along your protein. the MW cutoff of the membrane you are using to concentrate is important relative to the size of the free detergent micelle and of course the protein-detergent micelle you are trying to concentrate. too much detergent staying around is a major cause of trouble (i.e. poor diffraction and phase separation competing with productive crystal growth) besides many other parameters
Hope this helps -- Pascal F. Egea, PhD Assistant Professor UCLA, David Geffen School of Medicine Department of Biological Chemistry Boyer Hall room 356 611 Charles E Young Drive East Los Angeles CA 90095 office (310)-983-3515 lab (310)-983-3516 email pe...@mednet.ucla.edu On Thu, May 9, 2013 at 8:34 AM, RHYS GRINTER <r.grinte...@research.gla.ac.uk > wrote: > Hi All, > > A quick question if you've ever worked on membrane proteins, I'm trying to > optimize crystals for bacterial integral outer membrane protein I'm working > on. I'm getting some fairly modest rod like crystals in a 0.1M Tris pH > 7.5, 30% PEG 600, 0.03M MgCl2 condition. However I get lots and lots of > birefringent gel forming in the same condition, I get the feeling that this > is Detergent/Protein complex and is robbing my crystals of material to grow > bigger. > These crystals diffract to 5 A so I'd quite like to make them bigger and > better, > > Cheers, > > Rhys
