First few reflections seem characteristic of lamellar (rather than 3D crystals). Might be something other than PEG but see Magda El Nokaly, Stig E. Friberg, David W. Larsen, Lyotropic liquid crystals from lecithin, water, and polyethylene glycol, Journal of Colloid and Interface Science, Volume 98, Issue 1, March 1984, Pages 274-276, ISSN 0021-9797, DOI: 10.1016/0021-9797(84)90507-1. (http://www.sciencedirect.com/science/article/B6WHR-4RKW3SB-19/2/795b52beefd22e48f1958c167d9f4d0a)
Colin > -----Original Message----- > From: Jacob Keller [mailto:[email protected]] > Sent: 06 April 2011 18:16 > To: Nave, Colin (DLSLtd,RAL,DIA) > Cc: [email protected] > Subject: **Possible spam**Re: [ccp4bb] FW: [ccp4bb] diffraction of > spherulites > > 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 <[email protected]> > 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:[email protected]] On Behalf Of > Stefan > > Münnich > > Sent: 06 April 2011 09:33 > > To: [email protected] > > 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: [email protected] > *******************************************
