Hi Marcus, I think you misinterpret my comments :) My first point is not that my specific proteins make it easy to distinguish salt from protein visually - it's rather that I am experienced enough and also know enough chemistry to make an educated conclusion about the contents of my drops. I expect this to be an entirely trainable skill since only very rudimentary inorganic chemistry knowledge is sufficient to knock off about 80% of all salt crystals based simply on the knowledge of drop contents, and the rest is experience that anyone with 1-2 years of crystallization practice can obtain.
The crystal challenge while entertaining is nothing like the real world. In the real world I know what's in my drop, and in the real world I yet have to encounter a situation with TWO crystals in one drop of which only ONE is good, and the other will DIE as soon as I harvest the other one. This is too dramatic. Is this some sort of a Shroedinger crystal? Are the two crystals quantum-entangled? Crystallization is not a game, and if I only have one good crystal *ever* then I am not likely to get a structure, even if I know where that crystal is (we're talking new structure here, not a soak of a compound or a close MR, in which case there should not ever be only one crystal). Why don't I have more drops like this so I can harvest a couple of different crystals and get an actual dataset in the process? Come on. Likewise, most of the crystals in the challenge are way too huge - most hits aren't anywhere near that size which makes me wonder about the usefulness of the device in question for small nasty crystals - which are by far more common than the fat shiny ones that feature prominently in the challenge. On the subject of finding 'the best' crystals in a drop, or in a plate: if this was an actual syncrotron-quality beam capable of telling me right away that some of my 10x20x10 micron crystals are better than others then I would be much more curious. I however doubt that the instrument in question is very useful for crystals that are smaller than say 100x50x50 micron (assuming modest unit cell dimensions). As to the price - like you say the proof is in the pudding. The word 'considerable' is subject to *considerable* variance of meaning. For example, the actual price can be $390K which is a price of a cheap car's worth less than my original estimate of $400K -- is this considerable or not and more importantly is it still too much with respect to the value/price ratio? To me personally $10K is a lot, but the price/value ratio is still not favorable, the price would have to be around $80-90K to become interesting to me personally. I understand that it is not likely that the instrument of this sort can cost this little with today's technology. Which is why the cost/value matters :) Suppliers are reluctant to post specific prices of non-commodity items because then everyone would want to negotiate down from the same position - that's understandable, but I am not an equipment manufacturer and therefore I can understand but I do not have to sympathize. Without the actual price you can't really argue. And that's what brings me to the point that several others have made, which is that the etiquette of this board has always been to avoid direct advertisement. In my opinion it would have been more tactful to comment that 'direct X-ray study of crystals in-situ is a cool way to discover interesting things about your crystals' and leave the specific instrument that you sell to be discovered by whoever wants to dig deeper. Cheers, Artem On Tue, Apr 19, 2011 at 2:22 AM, <[email protected]> wrote: > > > > > > > Dear Artem, > > > > > > Thanks for your reply. You raise a number of points. > > > > Immediately, I should comment that the price of the PX Scanner is very > > considerably less than the $400k that you mention. > > > > Whilst - with the proteins and crystallisation conditions that you may be > working > > with, visual inspection may be sufficient to differentiate salt from > protein > > crystals (as you suggest), you will accept that generally this may not be > the > > case. Thus, ‘direct’ inspection, using X-rays, must surely be the most > appropriate way ? > > As you will be aware, the best looking crystals are seldom the best > diffracting. > > This is well demonstrated through the PX Scanner ‘Crystal Challenge’, of > course. > > Clearly, that’s another prime purpose of the PX Scanner: to identify the > ‘best’ crystals > > from amongst a multitude of candidates in a single droplet or across a > plate, etc. > > Also, using the PX Scanner, we can check the effect of added cryo-protect. > *prior* to > > freezing. > > > > Therefore, with this range of uses, the PX Scanner is clearly not intended > for full > > ‘data-collection’ – but rather to most effectively support crystallisation > optimisation and > > as a complement to in-house and central facility data-collection work. > From the feedback > > that we receive, the PX Scanner is much valued by the number of groups > which are > > now using these systems worldwide. > > > > However, even the proof of Grandma’s apple pie is not until the eating. > Accordingly, > > we most cordially invite you to visit one of our application labs – or > perhaps one of our > > customer sites (by arrangement), with you, hopefully, being able to bring > one or more > > of your crystallisation plates for inspection using the PX Scanner system. > Since you > > are based in North America, I believe, one of my responsible colleagues > will take up > > this invitation with you, off-BB. > > > > > > We look forward to our continuing discussions – with yourself, and all > others who > > may be interested. > > > > Many Thanks and Best Regards, > > > > Marcus Winter (Agilent Technologies) > > > > > > [image: > signature_crystalchall]<http://www.chem.agilent.com/en-US/Products/Instruments/X-raycrystallography/Pages/Crystalchallenge.aspx?cid=4710> > > > > > > *From:* Artem Evdokimov [mailto:[email protected]] > *Sent:* 19 April 2011 02:50 > *To:* WINTER,MARCUS (A-UnitedKingdom,ex1) > *Cc:* [email protected] > > *Subject:* Re: [ccp4bb] viewing and scoring diffraction using the PX > Scanner > > > > > > Hi, > > > > So what's your secret - how did you pack an entire synchrotron into a > little box? > > > > OK, so I am being facetious a little. However, I cannot help asking myself > why would I want to spend so much money on a system that is basically a > (vertical) X-ray diffractometer in a box, with fixed distance, and sans the > ability to collect data? I can only guess that the system costs in the range > of $400K (am I right?) and for that money one could get a pretty nice actual > X-ray diffraction set-up... > > > > Now, if this thing cost say ... $80K I may be interested, although most of > our crystals are so small that this set-up will uniformly score them as 'no > idea' because they don't even diffract at home on a 'real' X-ray source with > a CCD. > > > > Artem > > P.S. the day I start routinely confusing protein and salt crystals is the > day I stop working in the lab :) > > On Mon, Apr 18, 2011 at 3:00 AM, Marcus Winter <[email protected]> > wrote: > > > > > > > > Dear Chris, > > > > > > I’m prompted by your posting just to mention the Agilent Technologies > > PX Scanner ‘Crystal Challenge’ at: > > > > www.agilent.com/chem/crystalchallenge > > > > Thus, the only *really useful* assessment, or ‘score’, of objects > (putative > > crystals) – or crystallisation conditions, is by the actual observed > diffraction > > characteristics... and these preferably directly in situ, in the horizontal > > > crystallisation plate, as achieved in the PX Scanner. > > > > > > Many Thanks and Best Regards, > > > > Marcus Winter (Agilent Technologies) > > > > > > [image: > signature_crystalchall]<http://www.chem.agilent.com/en-US/Products/Instruments/X-raycrystallography/Pages/Crystalchallenge.aspx?cid=4710> > > > > > > > > *From:* CCP4 bulletin board [mailto:[email protected]] *On Behalf Of > *Chris > Ulens > *Sent:* 18 April 2011 08:24 > *To:* [email protected] > *Subject:* [ccp4bb] viewing and scoring crystallization drops on the iPad > > > > Our laboratory has been developing an application to view and score > crystallization drops on the iPad. We would like to know if > crystallographers see potential benefits from the functionality of the iPad > to swipe and pinch through drops. We are looking for specific comments from > Formulatrix users, but other users are also welcome to comment. > > > > http://www.youtube.com/watch?v=LezurNhm0pA > > > > > > Specific ideas for future development are: > > - composition of crystallization buffers on a back-flip of the image drop > > - back-sync of crystallization scores on the iPad with the image database > > - emailing a drop image to colleague > > > > Thanks. > > -Chris > > > > --------------------------------------------------- > > Chris Ulens, Ph.D. > > Lab of Structural Neurobiology > > Department of Molecular Cell Biology > > Campus Gasthuisberg, ON1 > > Herestraat 49, PB 601 > > B-3000 Leuven > > Belgium > > http://www.xtal.be > > > > >
