If your precipitant is high concentration salt, there will be a significant freezing point depression (see e.g. wikipedia entry http://en.wikipedia.org/wiki/Freezing-point_depression ). I seem to remember collecting data from crystals we cooled to -15 C in the early '80s. The crystals were grown in 2.4M Ammonium sulphate and harvested into 2.8M. Its true they were grown at room temperature but this would suggest there is no reason crystals could not be grown from high salt concentrations between 0 and whatever freezing point your precipitant solution has. Peter
On 30 May 2013 15:25, Matthew Franklin <mfrank...@nysbc.org> wrote: > Hi Glenn - > > I have nothing systematic, but I remember that transducin-alpha (1TND) was > crystallized at -12 C, with 20% glycerol in the mother liquor. (The > crystals grew at higher temperatures, but weren't as good.) I worked on > this project briefly in grad school, and I remember that looking at the > crystals was a big nuisance - you had to take the trays out of the -12 > freezer, run to the cold room, and look at them quickly before they warmed > up too much! > > - Matt > > > > On 5/30/13 7:26 AM, Glenn Masson wrote: > > Hello CCP4BBers, > > I am currently playing with some crystals that seem to enjoy lower > temperatures, and I was thinking of breaking the 0°C threshold. > > Looking for examples of this in the literature is problematic, as > searching for examples in the PDB (Under the advanced search-> crystal > properties-> temperature (K)) turns up a large amount of false positives. > Many otherwise supremely intelligent people seem unable or unwilling to > grasp the concept of Kelvin (it's amazing how many protein structures were > solved only 22 degrees above absolute zero...). > > I was wondering if anyone has much experience in this area? I see a few > structures e.g. 2Z97 (-5°C) and 4H0W (-2°C), but I was wondering if anyone > has a more systematic knowledge, some more examples, and what the > parameters and best practice of this technique are. > > Many thanks, > > Glenn Masson > > MRC-Laboratory of Molecular Biology > > > > -- > Matthew Franklin, Ph. D. > Senior Scientist > New York Structural Biology Center > 89 Convent Avenue, New York, NY 10027(212) 939-0660 ext. 9374 > >
