Actually, to echo Ron, many low-temperature/freezing/vitrification crystal experiments were done in the 1970's, some by Tsernoglou and Petsko, when they were both at Wayne State, I believe. However, the direction Jacques Dubochet was looking at was an extension of work from the early 1960's. EM researchers were looking at freezing of tissues for freeze-fracture imaging. They have tomes about freezing and the different zones of ice crystal formation and vitrification. In fact to bring it full circle, these electron microscopists cite Kathleen Lonsdale (of the International Tables fame) and here work on ice crystal diffraction in the 1950's.
While I was trying to stay out of this discussion, I am in favor of "flash-freezing" or "flash-cooling" and have no problem with the word frozen to describe a crystal in liquid N2, regardless of the crystallinity (or lack thereof) of the ice. This is the exact opinion of the electron microscopists doing freeze-fracture imaging for over 50 years: the tissue was frozen with a cryogen (e.g., freon), and you looked for the regions that were vitrified. My 2 cents. Cheers, Michael **************************************************************** R. Michael Garavito, Ph.D. Professor of Biochemistry & Molecular Biology 603 Wilson Rd., Rm. 513 Michigan State University East Lansing, MI 48824-1319 Office: (517) 355-9724 Lab: (517) 353-9125 FAX: (517) 353-9334 Email: rmgarav...@gmail.com **************************************************************** On Nov 16, 2012, at 1:26 PM, Ronald E Stenkamp wrote: > I'm a little confused. Petsko and others were doing > low-temperature/freezing/vitrification crystal experiments in the 1970s, > right? (J. Mol. Biol., 96(3) 381, 1975). Is there a big difference between > what they were doing and what's done now. > > Ron > > On Fri, 16 Nov 2012, Gerard Bricogne wrote: > >> Dear all, >> >> I think we are perhaps being a little bit insular, or blinkered, in >> this discussion. The breakthrough we are talking about, and don't know how >> to call, first occurred not in crystallography but in electron microscopy, >> in the hands of Jacques Dubochet at EMBL Heidelberg in the early 1980s (see >> for instance http://www.unil.ch/dee/page53292.html). It made possible the >> direct imaging of molecules in "vitrified" or "vitreous" ice and to achieve >> higher resolution than the previous technique of negative staining. In that >> context it is obvious that the vitreous state refers to water, not to the >> macromolecular species embedded in it: the risk of a potential oxymoron in >> the crystallographic case arises from trying to choose a single adjective to >> qualify a two-component sample in which those components behave differently >> under sudden cooling. >> >> I have always found that an expression like "flash-frozen" has a lot >> going for it: it means that the sample was cooled very quickly, so it >> describes a process rather than a final state. The fact that this final >> state preserves the crystalline arrangement of the macromolecule(s), but >> causes the solvent to go into a vitreous phase, is just part of what every >> competent reviewer of a crystallographic paper should know, and that ought >> to avoid the kind of arguments that started this thread. >> >> >> With best wishes, >> >> Gerard. >> >> -- >> On Thu, Nov 15, 2012 at 11:35:46PM -0700, Javier Gonzalez wrote: >>> Hi Sebastiano, >>> >>> I think the term "vitrified crystal" could be understood as a very nice >>> oxymoron (http://www.oxymoronlist.com/), but it is essentially >>> self-contradictory and not technically correct. >>> >>> As Ethan said, "vitrify" means "turn into glass". Now, a glass state is a >>> disordered solid state by definition, then it can't be a crystal. A >>> vitrified crystal would be a crystal which has lost all three-dimensional >>> ordering, pretty much like the material one gets when using the wrong >>> "cryo-protectant". >>> >>> What one usually does is to soak the crystal in a "cryo-protectant" and >>> then flash-freeze the resulting material, hoping that the crystal structure >>> will be preserved, while the rest remains disordered in a solid state >>> (vitrified), so that it won't produce a diffraction pattern by itself, and >>> will hold the crystal in a fixed position (very convenient for data >>> collection). >>> >>> Moreover, I would say that clarifying a material is vitrified when >>> subjected to liquid N2 temperatures would be required only if you were >>> working with some liquid solvent which might remain in the liquid phase at >>> that temperature, instead of the usual solid disordered state, but this is >>> never the case with protein crystals. >>> >>> So, I vote for "frozen crystal".- >>> >>> Javier >>> >>> >>> PS: that comment by James Stroud "I forgot to mention that if any >>> dictionary is an authority on the very cold, it would be the Penguin >>> dictionary.", is hilarious, we need a "Like" button in the CCP4bb list! >>> >>> -- >>> Javier M. Gonzalez >>> Protein Crystallography Station >>> Bioscience Division >>> Los Alamos National Laboratory >>> TA-43, Building 1, Room 172-G >>> Mailstop M888 >>> Phone: (505) 667-9376 >>> >>> >>> On Thu, Nov 15, 2012 at 2:24 PM, Craig Bingman >>> <cbing...@biochem.wisc.edu>wrote: >>> >>>> "cryopreserved" >>>> >>>> It says that the crystals were transferred to cryogenic temperatures in an >>>> attempt to increase their lifetime in the beam, and avoids all of the other >>>> problems with all of the other language described. >>>> >>>> I was really trying to stay out of this, because I understand what >>>> everyone means with all of their other word choices. >>>> >>>> On Nov 15, 2012, at 2:07 PM, James Stroud wrote: >>>> >>>>> Isn't "cryo-cooled" redundant? >>>>> >>>>> James >>>>> >>>>> On Nov 15, 2012, at 11:34 AM, Phil Jeffrey wrote: >>>>> >>>>>> Perhaps it's an artisan organic locavore fruit cake. >>>>>> >>>>>> Either way, your *crystal* is not vitrified. The solvent in your >>>> crystal might be glassy but your protein better still hold crystalline >>>> order (cf. ice) or you've wasted your time. >>>>>> >>>>>> Ergo, "cryo-cooled" is the description to use. >>>>>> >>>>>> Phil Jeffrey >>>>>> Princeton >>>>>> >>>>>> On 11/15/12 1:14 PM, Nukri Sanishvili wrote: >>>>>>> s: An alternative way to avoid the argument and discussion all together >>>>>>> is to use "cryo-cooled". >>>>>>> Tim: You go to a restaurant, spend all that time and money and order a >>>>>>> fruitcake? >>>>>>> Cheers, >>>>>>> N. >>>>>>> >>>> >> >> -- >> >> =============================================================== >> * * >> * Gerard Bricogne g...@globalphasing.com * >> * * >> * Global Phasing Ltd. * >> * Sheraton House, Castle Park Tel: +44-(0)1223-353033 * >> * Cambridge CB3 0AX, UK Fax: +44-(0)1223-366889 * >> * * >> =============================================================== >>
