Hi. I noticed long, needle crystals in that very condition (A1 using the Molecular Dimensions kit) for the protein that I am working with one day. I tried to optimize that condition not long ago using reagents in my lab. I did not have a problem with precipitation until using high concentrations of Li2SO4 (I think 1 M or so). However, all of my effort was really just a waste of time. The next day, I looked back at the crystallization condition and discovered huge, identical crystals had formed in the reservoir as well. I'd say make sure that you actually have a protein crystal to begin with before optimizing, because it is likely that the crystal is just salt.
> Hi All, > > there is a condition in the JCSG+ screen (0.2M Li2SO4, 0.1M NaOAc pH 4.5, > 50.0% v/v PEG-400) which forms heavy precipitate when made here in the > lab. > I assume that the order of addition of compounds might make a difference, > but doesn't this suggest that there is a high probabilty for salt crystals > under these conditions? How stable can this solution be? An > anecdotes/advice > appreciated. > > I assume that the PEG makes Li2SO4 fall out of solution, or perhaps it is > the pH? > > Jacob Keller > > ******************************************* > Jacob Pearson Keller > Northwestern University > Medical Scientist Training Program > Dallos Laboratory > F. Searle 1-240 > 2240 Campus Drive > Evanston IL 60208 > lab: 847.491.2438 > cel: 773.608.9185 > email: j-kell...@northwestern.edu > ******************************************* >
