Re: [ccp4bb] Mounting needle-shaped crystals
Dear Jack I can certainly recommend using the litholoops from molecular dimensions to mount the crystal you descibe. Most of the membrane crystal we start out with come as needles, the advantages is as mention before that the slight twist in the nylon loops isn't present. We do not have much success with the litholoops looking like little rackets. best Preben Tanner, John J. wrote: Dear CCP4, I'm looking for advice on mounting thin needles for low temperature data collection. Our needles are fairly long (100-200 microns) but only 20 microns or less thick. When I pick them up with Hampton loops (0.05-0.1 mm size), the crystals tend to break as they are moved out of the drop and through the liquid-air interface. I see that Mitegen sells MicroLoops E, which are advertised as working well for mounting needles. Can anyone recommend them? Can anyone recommend Mitegen MicroMeshes or another tool for mounting needles? Thanks, Jack Tanner -- Jens Preben Morth, Ph.D Aarhus University Department of Molecular Biology Gustav Wieds Vej 10 C DK - 8000 Aarhus C Tel. +45 8942 5025, Fax. +45 8612 3178 j...@mb.au.dk website: http://person.au.dk/da/j...@mb
Re: [ccp4bb] Mounting needle-shaped crystals
Hi Charlie, The bending of needles is hard to avoid :) My advice is to investigate different areas of the needle using finely focused beam - in particular focus on the protruding end and on the area inside the loop. The protruding area is particularly good since it has the least solvent attached to it. One of those may work out :) There's an alternative to this and that's using a very large loop so the needle never touches the nylon. The disadvantage of this approach is obviously the large volume of solvent/oil present in the loop, resulting in large background scatter. As far as systematic absences lost due to special orientation - yes, although if you have a bent loop (similar to the cheater pins from the bygone days) that's not much of an issue. Additionally, precise selection of space group can be always made as the structure's solved :) Artem Useful summary, Artem. Two comments spring to mind. - I have had trouble with slight bending of needles when frozen like this, causing problems with mosaicity. (Presumably due to different forces acting on the parts of the crystal within and without the loop.) - You can have lots of trouble measuring systematic absences in crystals mounted like this as the unique axis in hexagonal or tetragonal is close to the rotation axis. Cheers, Charlie Artem Evdokimov wrote: Sorry, hit send by accident. Here it is: http://www.xtals.org/pdfs/needles.pdf Artem -Original Message- From: Artem Evdokimov [mailto:ar...@xtals.org] Sent: Monday, October 05, 2009 9:05 PM To: 'Tanner, John J.'; 'CCP4BB@JISCMAIL.AC.UK' Subject: RE: [ccp4bb] Mounting needle-shaped crystals Hello felow MO crystallographer, For all it's worth, a while ago I've compiled a little document which describes mounting needles. I've converted it into PDF and posted it here: Nothing is built on stone; all is built on sand, but we must build as if the sand were stone Jorge Luis Borges -Original Message- From: CCP4 bulletin board [mailto:ccp...@jiscmail.ac.uk] On Behalf Of Tanner, John J. Sent: Monday, October 05, 2009 5:52 PM To: CCP4BB@JISCMAIL.AC.UK Subject: [ccp4bb] Mounting needle-shaped crystals Dear CCP4, I'm looking for advice on mounting thin needles for low temperature data collection. Our needles are fairly long (100-200 microns) but only 20 microns or less thick. When I pick them up with Hampton loops (0.05-0.1 mm size), the crystals tend to break as they are moved out of the drop and through the liquid-air interface. I see that Mitegen sells MicroLoops E, which are advertised as working well for mounting needles. Can anyone recommend them? Can anyone recommend Mitegen MicroMeshes or another tool for mounting needles? Thanks, Jack Tanner -- Charlie Bond Professorial Fellow University of Western Australia School of Biomedical, Biomolecular and Chemical Sciences M310 35 Stirling Highway Crawley WA 6009 Australia charles.b...@uwa.edu.au +61 8 6488 4406
Re: [ccp4bb] Mounting needle-shaped crystals
I must agree that the less stressed part of a needle may be the end not contacting the loop or meniscus, but protrudes out the end/top. One can carefully manipulate the crystal so that it is not parallel with the pin either by having a bent loop or setting the crystal slightly diagonal to the loop. If it is held out long enough, then only that part is in the beam with no background from the loop or mother liquor. In fact, I have seen where the meniscus was the problem as it curved the crystal in questionthe part overhanging the loop diffracting quite nicely. Additionally, small molecule people will regularly use a small dab of grease (I prefer Apiezon N) on a loop or fiber to adhere the crystal and remove it from the batch...then freeze it. The advantage is simplicity, and one can remove a crystal from virtually all mother liquor. The disadvantages are it a bare crystal free from all liquor (must be frozen ASAP before it dehydrates) and depending on your skill and luck sometimes one gets more than one crystal. Finally, if there is a worry about dehydration, a tip is to move the crystal from the crystallization drop to oil increasing time for manipulation. (Again, my preference is PFPE). Kris PS For a thin layer of grease, try disolving the grease in a volatile solvent, dipping the loop or fiber in the solution, and let dry. From: Jürgen Bosch jubo...@jhsph.edu To: CCP4BB@JISCMAIL.AC.UK Sent: Tuesday, October 6, 2009 9:04:51 AM Subject: Re: [ccp4bb] Mounting needle-shaped crystals Hi Jack, you could try the following strategy: a) use a larger loop than your needle, then before freezing carefully dip the loop onto the glass slide to reduce the amount of liquid b) if your crystal is larger than your largest loop cut it c) see attached figure. The way I mount those type of crystals is not to break through the surface but instead to retract the loop and lift the crystal out of the drop. The tip of the crystal comes out as last. Typically the part of the crystal in the loop has a higher mosaicity due to this treatment as you slightly need to bend the crystal when fishing it out of the drop. d) The Mitegen loops are very useful Good luck, Jürgen On Oct 5, 2009, at 6:52 PM, Tanner, John J. wrote: Dear CCP4, I'm looking for advice on mounting thin needles for low temperature data collection. Our needles are fairly long (100-200 microns) but only 20 microns or less thick. When I pick them up with Hampton loops (0.05-0.1 mm size), the crystals tend to break as they are moved out of the drop and through the liquid-air interface. I see that Mitegen sells MicroLoops E, which are advertised as working well for mounting needles. Can anyone recommend them? Can anyone recommend Mitegen MicroMeshes or another tool for mounting needles? Thanks, Jack Tanner -- John J. Tanner Professor of Chemistry and Biochemistry University of Missouri-Columbia 125 Chemistry Building Columbia, MO 65211 Phone: 573-884-1280 Fax: 573-882-2754 Email: tanne...@missouri.edu http://www.chem.missouri.edu/TannerGroup/tanner.html - Jürgen Bosch Johns Hopkins Bloomberg School of Public Health Department of Biochemistry Molecular Biology Johns Hopkins Malaria Research Institute 615 North Wolfe Street, W8708 Baltimore, MD 21205 Phone: +1-410-614-4742 Lab: +1-410-614-4894 Fax: +1-410-955-3655 http://web.mac.com/bosch_lab/
[ccp4bb] Mounting needle-shaped crystals
Dear CCP4, I'm looking for advice on mounting thin needles for low temperature data collection. Our needles are fairly long (100-200 microns) but only 20 microns or less thick. When I pick them up with Hampton loops (0.05-0.1 mm size), the crystals tend to break as they are moved out of the drop and through the liquid-air interface. I see that Mitegen sells MicroLoops E, which are advertised as working well for mounting needles. Can anyone recommend them? Can anyone recommend Mitegen MicroMeshes or another tool for mounting needles? Thanks, Jack Tanner -- John J. Tanner Professor of Chemistry and Biochemistry University of Missouri-Columbia 125 Chemistry Building Columbia, MO 65211 Phone: 573-884-1280 Fax: 573-882-2754 Email: tanne...@missouri.edu http://www.chem.missouri.edu/TannerGroup/tanner.html
Re: [ccp4bb] Mounting needle-shaped crystals
Hello felow MO crystallographer, For all it's worth, a while ago I've compiled a little document which describes mounting needles. I've converted it into PDF and posted it here: Nothing is built on stone; all is built on sand, but we must build as if the sand were stone Jorge Luis Borges -Original Message- From: CCP4 bulletin board [mailto:ccp...@jiscmail.ac.uk] On Behalf Of Tanner, John J. Sent: Monday, October 05, 2009 5:52 PM To: CCP4BB@JISCMAIL.AC.UK Subject: [ccp4bb] Mounting needle-shaped crystals Dear CCP4, I'm looking for advice on mounting thin needles for low temperature data collection. Our needles are fairly long (100-200 microns) but only 20 microns or less thick. When I pick them up with Hampton loops (0.05-0.1 mm size), the crystals tend to break as they are moved out of the drop and through the liquid-air interface. I see that Mitegen sells MicroLoops E, which are advertised as working well for mounting needles. Can anyone recommend them? Can anyone recommend Mitegen MicroMeshes or another tool for mounting needles? Thanks, Jack Tanner -- John J. Tanner Professor of Chemistry and Biochemistry University of Missouri-Columbia 125 Chemistry Building Columbia, MO 65211 Phone: 573-884-1280 Fax: 573-882-2754 Email: tanne...@missouri.edu http://www.chem.missouri.edu/TannerGroup/tanner.html
Re: [ccp4bb] Mounting needle-shaped crystals
Useful summary, Artem. Two comments spring to mind. - I have had trouble with slight bending of needles when frozen like this, causing problems with mosaicity. (Presumably due to different forces acting on the parts of the crystal within and without the loop.) - You can have lots of trouble measuring systematic absences in crystals mounted like this as the unique axis in hexagonal or tetragonal is close to the rotation axis. Cheers, Charlie Artem Evdokimov wrote: Sorry, hit send by accident. Here it is: http://www.xtals.org/pdfs/needles.pdf Artem -Original Message- From: Artem Evdokimov [mailto:ar...@xtals.org] Sent: Monday, October 05, 2009 9:05 PM To: 'Tanner, John J.'; 'CCP4BB@JISCMAIL.AC.UK' Subject: RE: [ccp4bb] Mounting needle-shaped crystals Hello felow MO crystallographer, For all it's worth, a while ago I've compiled a little document which describes mounting needles. I've converted it into PDF and posted it here: Nothing is built on stone; all is built on sand, but we must build as if the sand were stone Jorge Luis Borges -Original Message- From: CCP4 bulletin board [mailto:ccp...@jiscmail.ac.uk] On Behalf Of Tanner, John J. Sent: Monday, October 05, 2009 5:52 PM To: CCP4BB@JISCMAIL.AC.UK Subject: [ccp4bb] Mounting needle-shaped crystals Dear CCP4, I'm looking for advice on mounting thin needles for low temperature data collection. Our needles are fairly long (100-200 microns) but only 20 microns or less thick. When I pick them up with Hampton loops (0.05-0.1 mm size), the crystals tend to break as they are moved out of the drop and through the liquid-air interface. I see that Mitegen sells MicroLoops E, which are advertised as working well for mounting needles. Can anyone recommend them? Can anyone recommend Mitegen MicroMeshes or another tool for mounting needles? Thanks, Jack Tanner -- Charlie Bond Professorial Fellow University of Western Australia School of Biomedical, Biomolecular and Chemical Sciences M310 35 Stirling Highway Crawley WA 6009 Australia charles.b...@uwa.edu.au +61 8 6488 4406
