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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 <[log in to unmask]>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 [log in to unmask] * > * * > * Global Phasing Ltd. * > * Sheraton House, Castle Park Tel: +44-(0)1223-353033 * > * Cambridge CB3 0AX, UK Fax: +44-(0)1223-366889 * > * * > =============================================================== >