Not being in a model does not show that it's really not there. This is especially true when considering crystals that diffract to rather low resolution (~2.8 - 3.5+ Å).
You shouldn’t expect in that case to uniquely identify very many buffer components. Diana ************************************************** Diana R. Tomchick Professor Departments of Biophysics and Biochemistry University of Texas Southwestern Medical Center 5323 Harry Hines Blvd. Rm. ND10.214A Dallas, TX 75390-8816 diana.tomch...@utsouthwestern.edu<mailto:diana.tomch...@utsouthwestern.edu> (214) 645-6383 (phone) (214) 645-6353 (fax) On Sep 11, 2018, at 7:14 AM, Robbie Joosten <robbie_joos...@hotmail.com<mailto:robbie_joos...@hotmail.com>> wrote: Hi Tobias, I don't know of any specific claims made about this but you'd better check the data yourself if you find an example. A nice paper by Bill Hunter and his team (http://scripts.iucr.org/cgi-bin/paper?S1744309111005835) showed a case where Co2+ was an essential ion for crystallisation , but it was overlooked by the original depositors of the model. Not being in a model does not show that it's really not there. Cheers, Robbie -----Original Message----- From: CCP4 bulletin board <CCP4BB@JISCMAIL.AC.UK<mailto:CCP4BB@JISCMAIL.AC.UK>> On Behalf Of Tobias Beck Sent: Tuesday, September 11, 2018 13:42 To: CCP4BB@JISCMAIL.AC.UK<mailto:CCP4BB@JISCMAIL.AC.UK> Subject: Re: [ccp4bb] Literature on crystallization screen ingredients not showing up in crystal structure Thanks for the replies I have received so far (on and off list). I would like to emphasize an important aspect: What about crystallization trials where the ingredients do not show up, but cannot be omitted for the crystallization, e.g. buffers to control pH, as mentioned in one response - I am also thinking of specific ions, that are required, but are disordered - any general reference for this? Can't you just point out that crystallization is a purification method Yes, that would be one way to put it. Thanks, Tobias. On Tue, Sep 11, 2018 at 12:38 PM Patrick Shaw Stewart <patr...@douglas.co.uk<mailto:patr...@douglas.co.uk> <mailto:patr...@douglas.co.uk> > wrote: Can't you just point out that crystallization is a purification method? E.g. look at the number of proteins in the Sigma catalogue that have been purified by crystallization. Clearly crystallization often excludes other solutes in the mix. Best wishes, Patrick On Tue, 11 Sep 2018 at 08:41, Tobias Beck <tobiasb...@gmail.com<mailto:tobiasb...@gmail.com> <mailto:tobiasb...@gmail.com> > wrote: Dear all, I am looking for some general references regarding the fact that for a crystallization condition not all ingredients of the crystallization cocktail will show up in the crystal structure. Ions could be disordered, buffer components located in the solvent regions, etc. I think this is rather common knowledge, but maybe there is, especially regarding protein crystallization, a more general reference (apart from text books on solubility) for this and I am just not using the right search terms... Thank you! Best, Tobias. -- ___________________________________________ Dr. Tobias Beck - independent group leader - RWTH Aachen University Institute of Inorganic Chemistry Landoltweg 1, office: 304N 52056 Aachen, Germany phone: +49-241-80-90057 fax: +49-241-80-99003 web: http://www.ac.rwth-aachen.de/extern/beck/ ___________________________________________ ________________________________ To unsubscribe from the CCP4BB list, click the following link: https://www.jiscmail.ac.uk/cgi- bin/webadmin?SUBED1=CCP4BB&A=1 -- patr...@douglas.co.uk<mailto:patr...@douglas.co.uk> <mailto:patr...@douglas.co.uk> Douglas Instruments Ltd. Douglas House, East Garston, Hungerford, Berkshire, RG17 7HD, UK Directors: Peter Baldock, Patrick Shaw Stewart http://www.douglas.co.uk<http://www.douglas.co.uk/> Tel: 44 (0) 148-864-9090 US toll-free 1-877-225-2034 Regd. England 2177994, VAT Reg. GB 480 7371 36 <http://t.sidekickopen13.com/e1t/o/5/f18dQhb0S7kC8dDMPbW2n0x6l2B9g XrN7sKj6v5KRN6W56jV385v7rnbW4WDX_q2HNFv8f197v5Y04?si=700000000 1398361&pi=d783306d-9ddd-4cae-fcf9-ebed897fee90&ti=null> -- ___________________________________________ Dr. Tobias Beck - independent group leader - RWTH Aachen University Institute of Inorganic Chemistry Landoltweg 1, office: 304N 52056 Aachen, Germany phone: +49-241-80-90057 fax: +49-241-80-99003 web: http://www.ac.rwth-aachen.de/extern/beck/ ___________________________________________ ________________________________ To unsubscribe from the CCP4BB list, click the following link: https://www.jiscmail.ac.uk/cgi-bin/webadmin?SUBED1=CCP4BB&A=1 ######################################################################## To unsubscribe from the CCP4BB list, click the following link: https://www.jiscmail.ac.uk/cgi-bin/webadmin?SUBED1=CCP4BB&A=1 ________________________________ UT Southwestern Medical Center The future of medicine, today. ######################################################################## To unsubscribe from the CCP4BB list, click the following link: https://www.jiscmail.ac.uk/cgi-bin/webadmin?SUBED1=CCP4BB&A=1
