[ccp4bb] cryocrystals
Hi Does anybody know how long one could store a crystal in liquid nitrogen for before it will no longer diffract well? I'm talking in the order of weeks to months... careina
Re: [ccp4bb] cryocrystals
I dare say indefinitely. Your crystal life expectancy drops rapidly though with somebody not remembering to fill up the dewar. Transferring crystals to pucks etc. is another problem. I had some crystals which I could not remember what they were (label broke off the cane) and we simply reshoot them after 1 year and figured out it was the usual suspect from the cell dimensions. Jürgen On May 22, 2013, at 8:38 AM, Careina Edgooms wrote: Hi Does anybody know how long one could store a crystal in liquid nitrogen for before it will no longer diffract well? I'm talking in the order of weeks to months... careina .. Jürgen Bosch Johns Hopkins University Bloomberg School of Public Health Department of Biochemistry Molecular Biology Johns Hopkins Malaria Research Institute 615 North Wolfe Street, W8708 Baltimore, MD 21205 Office: +1-410-614-4742 Lab: +1-410-614-4894 Fax: +1-410-955-2926 http://lupo.jhsph.edu
Re: [ccp4bb] cryocrystals
careina Cryocrystals will last several months and more. Make sure that your LN2 is dry. On Wed, 22 May 2013 14:38:51 +0200, Careina Edgooms careinaedgo...@yahoo.com wrote: Hi Does anybody know how long one could store a crystal in liquid nitrogen for before it will no longer diffract well? I'm talking in the order of weeks to months... careina -- Enrico A. Stura D.Phil. (Oxon) ,Tel: 33 (0)1 69 08 4302 Office Room 19, Bat.152, Tel: 33 (0)1 69 08 9449Lab http://www-dsv.cea.fr/ibitecs/simopro/ltmb/cristallogenese LTMB, SIMOPRO, IBiTec-S, CE Saclay, 91191 Gif-sur-Yvette, FRANCE http://scholar.google.com/citations?hl=enuser=Kvm06WIoPAsCpagesize=100sortby=pubdate http://www.chem.gla.ac.uk/protein/mirror/stura/index2.html e-mail: est...@cea.fr Fax: 33 (0)1 69 08 90 71
Re: [ccp4bb] cryocrystals
in theory I would say decades/eons. in practice it probably depends on how much water/ice your liquid nitrogen contains, multiple refillings of the liquid nitrogen might slowly deposit tiny ice crystals on the crystals and slowly make diffraction worse... Mark J van Raaij Lab 20B Dpto de Estructura de Macromoleculas Centro Nacional de Biotecnologia - CSIC c/Darwin 3 E-28049 Madrid, Spain tel. (+34) 91 585 4616 http://www.cnb.csic.es/~mjvanraaij On 22 May 2013, at 14:38, Careina Edgooms wrote: Hi Does anybody know how long one could store a crystal in liquid nitrogen for before it will no longer diffract well? I'm talking in the order of weeks to months... careina
Re: [ccp4bb] cryocrystals
Theoretically? Millions to billions of years. Practically? They will last until the first time you forget to fill the dewar. Or until the Sun explodes and in the rush to leave Earth your descendants forget to pack it. Whichever comes first. Seriously, as long as the crystals have actually stayed below ~130 K they are as stable as glass beads. This is because they actually ARE glass beads at this temperature. The diffusion rate, however, goes up by a factor of a million at ~140K and that seems to be why there are so many rumors floating around out there that crystals change under lN2. Perhaps perpetuated by people who want space in the storage dewar. For example, there is a rumor that gasses like xenon will slowly leach out of cryo-cooled samples. I heard that one about 10 years ago, and since then I have been periodically checking the occupancy of the Xe sites in a particular cryo-cooled lysozyme crystal. So far, I can see no change. But if I ever make a mistake opening the tongs and warm it to 140K, even for a millisecond, I'm sure it will be ruined. As for ice that accumulates at 100K, this is always easy to remove with a jet of liquid nitrogen. We use this commercial product: http://brymill.com/brymill-cryosurgical-devices/brymill-cry-ac-cry-ac-3.html and there is a new one from MiTeGen http://www.mitegen.com/mic_catalog.php?c=iceoff which is cheaper as it is not a medical device. You just have to be careful not to knock the crystal off with it, and not to blow the cryo stream out of the way. Can't just point and shoot. You need to sweep the liquid stream over the crystal. It is surprisingly effective. You can also check out these studies on dewar life: http://dx.doi.org/10.1107/S0021889804025403 and on the thermal spike you can encounter while mounting/unmounting with cryovials: http://dx.doi.org/10.1007/s10969-007-9029-0 -James Holton MAD Scientist On 5/22/2013 5:38 AM, Careina Edgooms wrote: Hi Does anybody know how long one could store a crystal in liquid nitrogen for before it will no longer diffract well? I'm talking in the order of weeks to months... careina
