Depending on the crystal shape, "random orientation" is not always random. Many crystals have tendencies of sitting themselves in one predominant posture in the mount. Compounding this, many experimenters have tendencies of rotating the mount into a specific orientation when centering. Then crystal orientation ends up being not random at all, so understanding it's true orientation as my neighbor Frank suggests can be highly beneficial.
Cheers, N. Ruslan Sanishvili (Nukri), Ph.D. GM/CA-CAT Biosciences Division, ANL 9700 S. Cass Ave. Argonne, IL 60439 Tel: (630)252-0665 Fax: (630)252-0667 rsanishv...@anl.gov ________________________________ From: CCP4 bulletin board [mailto:CCP4BB@JISCMAIL.AC.UK] On Behalf Of Frank von Delft Sent: Friday, November 18, 2011 2:27 AM To: CCP4BB@JISCMAIL.AC.UK Subject: Re: [ccp4bb] crystal orientation during data collection I believe you achieve completeness more quickly (fewer crystals) if you just take random orientations. At least, that's what I learnt from Dave Stuart. phx On 18/11/2011 04:20, Frank Murphy wrote: Yanwu, I surmise from your question that you are inquiring how to go about collecting from many crystals optimally. Merging data ex post facto is a totally different kettle of fish. In my opinion, the most robust way to go about this is to use a kappa goniometer as Jim suggested (I am most familiar with the MK3). Since you intend to collect from many crystals, align the first and all subsequent crystals to the same easily attainable (or seemingly so) orientation, and then collect the sweep suggested by your data collection strategy program of choice. To achieve this at NE-CAT, we have a GUI-based system that used STAC for orientation determination and BEST for strategy generation. As Jim suggested, more options than STAC exist. If anyone is unable to get to a kappa goniometer, they can employ Mosflm or XDS (Xplan) to generate strategies for data collection from a crystal taking into account previously collected data. This is not nearly as robust a solution, but is a workable substitute (and also automated at NE-CAT). I know there are other ways to achieve similar results, but I have suggested the methods I am most familiar with... Yours, Frank Murphy Begin forwarded message: From: yanwu huo <applehu...@gmail.com> Date: November 17, 2011 4:00:06 PM CST To: CCP4BB@JISCMAIL.AC.UK Subject: [ccp4bb] crystal orientation during data collection Reply-To: yanwu huo <applehu...@gmail.com> Hi, I worked on a crystal sensitive to radiation damage, So I need to merge many crystal to obtain complete dataset, Does anyone know such program that can tell crystal orientation after first frame exposure. Thank you in advance. -- Thank you very much and all the best, Yanwu Huo Postdoctoral Associate Department of Molecular Biology and Genetics Cornell University Ithaca, NY, 14853 Email:yh...@cornell.edu <mailto:email%3ayh...@cornell.edu>
