With salt-based conditions sodium malonate is your friend: Acta Cryst D59: 2356
On Tue, 2009-12-15 at 12:20 +0000, Natalie Zhao wrote: > -----Original Message----- > From: owner-c...@dl.ac.uk [mailto:owner-c...@dl.ac.uk] On Behalf Of Rafael > Couñago > Sent: 14 December 2009 20:22 > To: c...@ccp4.ac.uk > Subject: [ccp4]: TDS upon flashcooling > > Dear all, > > I got these beautiful looking crystals that grow in high salt (1.8M) and > diffract under 2.0A at room temp. My attempts so far to cryo protect > them have resulted in a loss of resolution (2.5A tops) and increased > anisotropy. > > I have tried some of the usual suspects; no cryo, ethylene glycol, > glycerol (even 5% makes my crystal crack), sucrose, glucose, paratone-n > (no diffraction at all). I have tried both dipping the crystal straight > into liquid nitrogen and flash cooling it in the cryostream. > > An interesting observation is that the diffraction pattern following > freezing has a substantial amount of thermal diffuse scattering (but no > ice rings). If I remove the crystal from the cryostream and re-anneal > it at room temp (in air or in mother liquor or mother liquor + cryo) > most of the TDS goes away, but the max resolution is still around 2.5A > and the higher anisotropy is still there. Extending re-annealing times > lead to cracking of the crystal. > > My two questions would be: > > - any thoughts on cryo solutions? > - does the result from the re-annealing experiment ring any bells? > Would this be an indication that I need the cooling to be faster or slower? > > Cheers, > > Rafael. > > -- > Rafael Couñago > Research Fellow > Department of Biochemistry > University of Otago > > 710 Cumberland St > Dunedin, New Zealand > ph: (03) 479 5148 > -- Edwin Pozharski, PhD, Assistant Professor University of Maryland, Baltimore ---------------------------------------------- When the Way is forgotten duty and justice appear; Then knowledge and wisdom are born along with hypocrisy. When harmonious relationships dissolve then respect and devotion arise; When a nation falls to chaos then loyalty and patriotism are born. ------------------------------ / Lao Tse /
