It seems hard to imagine what there is anything in his solutions other than protein that would make spherulites, no? PEG 8000 at 12% seems pretty benign, unless the trays or screens have been sitting around for quite a while...
JPK On Wed, Apr 6, 2011 at 12:04 PM, Colin Nave <colin.n...@diamond.ac.uk> wrote: > > > Stefan > > Could the low angle reflections be from lamellar liquid crystals of the PEG > (or a mixed PEG/water phase). Seems like you have 1st,2nd and 4th order > reflections with presumably the 2nd order about 20A. > > I think 40A lamellar spacing is characteristic of some PEG liquid crystals. > > Colin > > > > > > From: CCP4 bulletin board [mailto:CCP4BB@JISCMAIL.AC.UK] On Behalf Of Stefan > Münnich > Sent: 06 April 2011 09:33 > To: CCP4BB@JISCMAIL.AC.UK > Subject: [ccp4bb] diffraction of spherulites > > > > Hey guys, > > > > > > When I collect data from these spherulites/crystals (grown in 0.1 M sodium > acetate, 0.1 M MOPS pH 7.5, 12 % (w/v) PEG-8000, protein buffer: 100 mM > NaCl, 50 mM HEPES pH 7.5): > > > > http://img695.imageshack.us/i/cryst.png/ > > > > I get this diffraction pattern: (it's not cryo protected, so there's some > ice-rings also) > > > > http://img683.imageshack.us/i/diffv.jpg/ > > > > It can't be only ice-rings because those are usually starting at something > like 3.8 A, whereas I already got one ring directly around the beam center > and also one at about 20 A. > > > > Has anybody seen anything like that and tell me what it is? > > > > > > Stefan -- ******************************************* Jacob Pearson Keller Northwestern University Medical Scientist Training Program cel: 773.608.9185 email: j-kell...@northwestern.edu *******************************************
