Hi Christine, I would try to optimize both conditions, provided that you do not have contradicting information (like a diffraction pattern that shows a small lattice - "salt"). Have you tried an additive screen? Have you tried adding a detergent?
My experience is mixed with things of that nature - sometimes you can get better looking "crystals", sometimes not. And you should always keep in mind that "looks" and "content" (and subsequently diffraction quality) are two different matters. Once I was taught a rule that in the case of protein-DNA complexes, the quality of diffraction is inversely proportional to the "prettiness" of the crystals and then I proved that rule wrong with nice-looking crystals that did diffract well. But it is true that crystals do not need to be pretty to be useful. So by all means, please do test diffraction. Good luck. Mark -----Original Message----- From: Harman, Christine <christine.har...@fda.hhs.gov> To: CCP4BB <CCP4BB@JISCMAIL.AC.UK> Sent: Wed, Jun 6, 2012 3:53 pm Subject: [ccp4bb] Are these xtal conditions worth optimizing? Hi All, I have these very weird drops that I found from screening (please find pictures attached). I am not sure if they are worth optimizing. I am very interesting to know your opinions of what you think of thesedrops could be (are these what you call "spherulites"?). If you think these conditions are worth optimizing, I welcome any ideas on how to optimize. I have done some optimization and still get the same result which is many of these weird things growing throughoutthe drop and with no sharp edges, and sometimes a skin forms after 2weeks (with the sodium malonate conditions only). I have also opened the drop and poked around to see if it is phase separation and this things are definitely solid and slightly-very mushy. I haven't had a chance to check for diffraction, but will be very soon. Both of these drops contain the same protein preparation of a Fab/peptide complex @ ~5mg/mL in buffer containing 0.1M Sodium Acetate pH 5, 150mM NaCl. I appreciate any advice, thoughtsor comments that you could provide. Peace, Christine
