Hi Peter, If the crystals are brownish, then it may be crystals of Hexamine cobalt (III) chloride. If you have the final dialysis buffer of the protein, setting up a crystallization trial with just the buffer may help you distinguish between salt and protein.
Hope this helps, Wataru On 2011/07/07, at 11:24, Peter Hsu wrote: > Wanted to get an opinion. I set up a screen a while ago and got these very > small cubic looking crystals 2-3 days later amidst a lot of precipitant. The > condition was Natrix E1 (0.04M LiCl, 0.02M MgCl2, 0.04M Sodium Cacodylate > pH5.5, 30% MPD, 0.02M Hexammine Cobalt (III) chloride). This protein's rather > difficult to make, and I don't have a lot of it left frozen in the fridge > after setting up the screens. Was wondering if anyone's ever observed salt > crystals forming from this condition before? My protein's in 20mM HEPES > pH7.5, 100mM NaCl, 5mM DTT. > > Thanks to all for any thoughts.
