You can also try to use the micromount loops (look like ink-pen nibs) sold by Mitegen. They are a
much easier alternative to capillary mounts; they are easy to handle and work well for room
temperature data collection.
Good luck.
Raji
---------Included Message----------
>At the risk of sounding too commercial, here are some suggestions:
>
>1. See if you can either place your crystallization tray in a cold room or
>crystallize it there. Mount your crystal in a capillary here so that at
>whatever lower temperature you use, the distillation of solvent will be
>reduced.
>
>2. If capillaries are too hard to work with, even a quick diffraction image
>out of a loop, while the crystal is drying out, may give you some
>information. Alternately, I have saturated my stock solution with sugar
>from the coffee room and swished my crystal through this for getting a quick
>diffraction image. In a rare case, the crystal actually diffracted for
>several hours at room temperature.
>
>3. Someone mentioned using Paratone oil. This is good, but a little thick
>and sticky. So, I use PerFluoroPolyEther (PFPE) as it is much less viscous
>and is colorless. I buy FOMBLIN Y VAC 14/6 from SigmaAldrich (Cat #
>317934-100G). PFPE is mildly hydroscopic, so it is best to open the bottle
>infrequently (I withdraw ten 0.5 ml aliquots whenever I open the bottle).
>
>4. The Free Mounting System (FMS) is ideal for RT screening. So long as
>you do not have a highly volatile component in solution, then you can use
>the standard FMS at temperatures in the range of 15 to 25 C. If you do have
>a volatile component, then Proteros bistructures GmbH (www.proteros.com) has
>the only FMS with the capability of adding solvents to the gas stream...and
>with some compensation, they will gladly help you with this.
>
>Kris
>
>------------
>Kris F. Tesh, Ph D
>Director, Macromolecular Products
>Rigaku Americas Corporation
>9009 New Trails Drive
>The Woodlands, TX 77381 USA
>001 281 362 2300 x 144
>-----Original Message-----
>From: CCP4 bulletin board [mailto:[log in to unmask]] On Behalf Of
>Benini, Stefano
>Sent: Wednesday, July 11, 2007 7:17 AM
>To: [log in to unmask]
>Subject: Re: [ccp4bb] Help with reducing crystal mosaicity
>
>Dear Mary,
>
>the problem encountered with cryoprotectans is the change in the solution
>surrounding your crystal as they may not be present in your crystallisation
>conditions or you need to increase their concentration to make them act as
>cryoprotectant.
>So I don't thik is the cryoprotectant itself as it is you mother liquor..
>
>test it in a capillary so you could rule out that freezing is the problem
>
>of course you don't want to find new crystallisation conditions when you
>tried everything and I know what it means!!
>
>I would try to improve crystal quality using additives or ligand etc....,
>
>your long axis is very worrying as well!!! may be some magic additive could
>change the packing and givew better diffraction too
>
>I also had crystals growing from MPD, unfortunately there was a
>non-cleavable his-tag
>so I could not hope that metals would help..... and other additives did not
>make any difference
>then my contract finished and so did the project!
>
>I hope you still have a lot of time available to try different things but I
>would not waste time trying to change your cryo
>
>ciao
>
>Stefano
>
>Stefano Benini PhD
>AstraZeneca UK
>Structural Biology
>Mereside 50S38
>Alderley Park
>
>
>
>
>
>
>
>
>-----Original Message-----
>From: CCP4 bulletin board [mailto:[log in to unmask]]On Behalf Of
>Patrick Shaw Stewart
>Sent: 11 July 2007 12:10
>To: [log in to unmask]
>Subject: Re: [ccp4bb] Help with reducing crystal mosaicity
>
>
>Just a thought, Mary - going back to your original question about MPD. I
>extracted the crystallization conditions from REMARK 280 of 3939 PDB entries
>a couple of years ago. The average concentration of the MPD used was high -
>38.6%, while PEGs tended to be used at lower concs, e.g. PEG400 25.7%. You
>can see the data at www.douglas.co.uk/top14.htm
>
>I thought this information could be useful if you want to replace some of
>the MPD with another precipitant (or cryoprotectant).
>
>Best wishes
>
>Patrick Shaw Stewart
>
>
>--
>[log in to unmask] Douglas Instruments Ltd.
>DouglasHouse, EastGarston, Hungerford, Berkshire, RG177HD, UK
>Directors: Peter Baldock, Patrick Shaw Stewart, James Smith
>http://douglas.co.uk or http://www.douglasinstruments.com
>Tel: 44 (0) 148-864-9090 US toll-free 1-877-225-2034
>Regd. England 2177994, VAT Reg. GB 480 7371 36
>
>
>> -----Original Message-----
>> From: CCP4 bulletin board [mailto:[log in to unmask]] On Behalf Of Mary
>> Fitzgerald
>> Sent: 09 July 2007 23:05
>> To: [log in to unmask]
>> Subject: [ccp4bb] Help with reducing crystal mosaicity
>>
>> Help please!
>>
>> I'm looking for some new ideas. I have crystals that come out of a
>> sitting drop with a mixture of sodium cacodylate at pH 6.5, magnesium
>> acetate and MPD for the well solution. The MPD concentration is
>> sufficient to act as a cryoprotectant. Currently, I directly freeze
>> these crystals in liquid nitrogen. When I collect data, I typically
>> have high anisotropic mosaicity; it ranges from 0.8 to 1.2. This is
>> further complicated with a weakly diffracting crystal (4-5 A) that has
>> a long unit cell axis of ~500 and often twinning.
>>
>> It has been suggested to me that the cryoprotectent is a problem. I
>> haven't checked the diffraction at room temperature, yet. Please no
>> suggestions of finding a different crystal form as that's not a
>> consideration at the moment. I have my reasons. I did find one
>> crystal that has lower mosaicity (0.5 to 0.8) but had weaker
>> diffraction then the typical crystal. Attempts at flash cryoannealing
>> have not helped.
>>
>> So, what's a good way to change the cryoprotectant if the
>> cryoprotectant is the precipitant? I've considered trying dehydration
>> but wasn't certain if that would help with the mosaicity.
>>
>> Thanks for any ideas,
>>
>> Mary X. Fitzgerald
>> Postdoctoral Associate
>
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