Chris,
Crystals can be very tollerant of cryo-solutions that respect the degree
of hydration
of the lattice. You can use any cryo-solution you want, including oil.
Try 10% Di-ethylene glycol, 10% 1.2-propanediol, 10% glycerol, 10% PEG
10K, 10% buffer solution, 1M NaCl
(pH close to the one you use now; slightly higher or lower may help).
1M NaCl should provide enough ionic strength for the duration of the
cryo-soak
to prevent the crystals from dissolving.
Test one crystal in this solution. If the crystals crack reduce the PEG
10K concentration
if they dissolve increase the NaCl concentration or try:
Try 8% Di-ethylene glycol, 8% 1.2-propanediol, 8% glycerol, 8% PEG 10K, 8%
MPD 10% buffer solution, 1M NaCl.
As already suggested cryosalts may work, but Ammonium di-hydrogen
phosphate 0.4M is on the low side
as far as ionic strength is concerned and if the crystals are very big
they are likely to crack. No problems
if you have needles or smallish crystals.
Enrico.
On Thu, 26 May 2011 13:01:08 +0200, <herman.schreu...@sanofi-aventis.com>
wrote:
Dear Chris,
I have not used this particular condition, but as a rule of thumb I use
"like with like", e.g. glycerol, ethylene glycol, PEG400 etc. with PEG
conditions, and saltlike compounds (sucrose, xylitol, salts) for salt
conditions. In your case I would try glucose or xylitol or just look
what happens if you increase the ammonium phosphate concentration to say
2M without adding glycerol.
Good luck!
Herman
-----Original Message-----
From: CCP4 bulletin board [mailto:CCP4BB@JISCMAIL.AC.UK] On Behalf Of
Chris Ulens
Sent: Thursday, May 26, 2011 12:27 PM
To: CCP4BB@JISCMAIL.AC.UK
Subject: Re: [ccp4bb] recommendation for ammonium dihydrogen phosphate
cryo
Hi,
I would like to get recommendations for a proper cryo solution for a
crystallization hit from the Hampton crystal screen Ammonium di-
hydrogen phosphate 0.4M. I tried increasing glycerol up to 30% with the
same ammonium phosphate concentration or increasing glycerol up to 30%
in the presence of 1.3M ammonium phosphate. Both gave iced up drops (I
only tried quick and dirty tests by dipping a cover glass in liquid
nitrogen).
Thank you.
-Chris
--
Enrico A. Stura D.Phil. (Oxon) , Tel: 33 (0)1 69 08 4302 Office
Room 19, Bat.152, Tel: 33 (0)1 69 08 9449 Lab
LTMB, SIMOPRO, IBiTec-S, CE Saclay, 91191 Gif-sur-Yvette, FRANCE
http://www-dsv.cea.fr/en/institutes/institute-of-biology-and-technology-saclay-ibitec-s/unites-de-recherche/department-of-molecular-engineering-of-proteins-simopro/molecular-toxinology-and-biotechnology-laboratory-ltmb/crystallogenesis-e.-stura
http://www.chem.gla.ac.uk/protein/mirror/stura/index2.html
e-mail: est...@cea.fr Fax: 33 (0)1 69 08 90 71
