Hi Dirk, I remember a neat paper don't recall who wrote it. I think it was in Acta D where the authors made a tiny probe the size of an elongated crystal glued to a [/Advertisement on] Hampton loop [/Advertisement off]. The probe was a temperature sensor and they recorded the cooling rate under different methods. The winner as far as I recall was freezing in liquid propane for the lack of the missing gas layer, but the second best method was LN2. Propane for whatever reason has gone extinct in certain areas of the world :-) . I'll try to find that reference but perhaps somebody else on this highly educated board knows which paper I'm referring to. I want to say it was published around 2004-2006.
Jürgen On Feb 7, 2012, at 11:12 AM, Dirk Kostrewa wrote: Dear Jürgen, Am 07.02.12 16:58, schrieb Bosch, Juergen: <snip> Then one last remark, LN2 versus cryo-stream freeze. Dipping in LN2 leads to a quicker freeze of your material. </snip> Are you sure? There was a publication by Warkentin et al. [1] about a cold gas layer above liquid nitrogen that reduces the expected cooling rate a lot! My very personal experience is, that cryo-cooling in the N2-stream worked better for me than in LN2 in a variety of projects - but the reason could just be me ;-) Best regards, Dirk. [1] Matthew Warkentin, Viatcheslav Berejnov, Naji S Husseini, and Robert E Thorne: "Hyperquenching for protein cryocrystallography", J. Appl. Crystallogr., 39, 805-811 (2006) -- ******************************************************* Dirk Kostrewa Gene Center Munich Department of Biochemistry Ludwig-Maximilians-Universität München Feodor-Lynen-Str. 25 D-81377 Munich Germany Phone: +49-89-2180-76845 Fax: +49-89-2180-76999 E-mail: [email protected]<mailto:[email protected]> WWW: www.genzentrum.lmu.de ******************************************************* ...................... 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://web.mac.com/bosch_lab/
