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Hi Steve, You can screen your crystals for the presence of twinning with a partial data set. I had a R3 crystal that experienced merohedral twinning and was able to identify single crystals from as little as 10 deg. of data. After scaling the data, I ran the intensities through Truncate and looked at the recommended statistics, 2nd moment and cummulative intensity distribution. This clearly identified single crystals. The good news for you is that 30% twin fraction is still very usable data. I solved my structure from a crystal with 45% twin fraction by MR. Good luck, Chris On Mon, 17 Jul 2006, Soisson, Stephen Michael wrote: >>>*** For details on how to be removed from this list visit the *** >>>*** CCP4 home page http://www.ccp4.ac.uk *** >>> >>> >>>Hi everyone, >>> >>>I hit the jackpot and got some beautiful crystals that are also beautifully >>>twinned. If there is any good news, it is that the twin fraction is about >>>0.3 for the first crystal that I collected data from. I know that some >>>people have collected data sets from multiple crystals until they find one >>>with a lower twin fraction, and I was wondering if you can do this with >>>partial data sets or if you need a full set? I suppose I could test this >>>out with some of my existing data; however, I thought I would pose the >>>question to see if anyone had direct experience with this that could offer >>>any good suggestions for how to deal with this. >>> >>>Many thanks in advance for your comments. >>> >>>Cheers, >>> >>>Steve >>> >>> >>> >>>------------------------------------------------------------------------------ >>>Notice: This e-mail message, together with any attachments, contains >>>information of Merck & Co., Inc. (One Merck Drive, Whitehouse Station, New >>>Jersey, USA 08889), and/or its affiliates (which may be known outside the >>>United States as Merck Frosst, Merck Sharp & Dohme or MSD and in Japan, as >>>Banyu) that may be confidential, proprietary copyrighted and/or legally >>>privileged. It is intended solely for the use of the individual or entity >>>named on this message. If you are not the intended recipient, and have >>>received this message in error, please notify us immediately by reply e-mail >>>and then delete it from your system. >>>------------------------------------------------------------------------------ >>> Christopher L. Colbert, Ph.D. Research Associate Phone: (214) 645 5944 University of Texas Southwestern Medical Center FAX: (214) 645 5945 6001 Forest Park Lane Dallas, TX 75390
