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Re: [ccp4bb] "Quick soak" method |
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CCP4bb navigationCCP4bb <-- 1999 <-- November 1999 <-- 30 November 1999Subject: Re: "Quick soak" method From: Juergen Bosch jbosch {- at -} U {- dot -} WASHINGTON {- dot -} EDU Date: 2007-09-25 There's a nice databank out there in the world wild web: http://www.sbg.bio.ic.ac.uk/had/ Juergen Derek Logan wrote: > Hi Uwe, > > Just what I wanted to hear, and with a limited set of compounds too! > Follow-up question: what are these 4-6 most successful compounds? > Thanks also for the tips on monitoring thw soaking > > Derek > > On Sep 25, 2007, at 13:23, Uwe Mueller wrote: > >> Dear Derek, >> we are using the quick-soak method frequently at the BESSY-MX >> beamlines. So far we were able to obtain phase information in terms >> of MAD/SAD- phases in all cases which we tried. The starting set-up >> is the screen over the 4-6 most successful heavy atom compounds at >> 5-10mM concentration and 10-20 min soaking time. >> If you follow the soaking under a transmissive light microscope like >> the Leica MZ7.5, you can receive quite intriguing visual feedbacks >> from your experimental set-up, including the bending of large >> crystal face areas towards the crystal center due to the large >> osmotic pressure at the beginning of the process an others. Those >> observations might provide you further information for the >> optimization loop which will be confirmed by the detection of an >> anomalous signal after the peak-dataset. >> 3-8 of such fast feedback loops could be carried out within a 8h >> beamtime shift and led to interpretable electron densities. So, I >> regard this method as a very powerful alternative, where the >> availability of SeMet-crystals is limited. >> >> Best regards, >> Uwe >> >> >> Derek Logan schrieb: >> >>> Hi, >>> >>> I'd like to find out how successful the "quick soak" method for >>> heavy atom derivatisation proposed by Radaev and Sun: >>> >>> Sun PD, Radaev S, Kattah M. Generating isomorphous heavy-atom >>> derivatives by a quick-soak method. Part I: test cases. Acta Cryst. >>> 2002. D58:1092-1098. >>> >>> has been in comparison to the "classical" method of longer soaks at >>> low concentrations of heavy atom compound. The method was quite >>> successful in our hands a few years ago but (fortunately?) it's >>> becoming increasingly rare that we use heavy atoms. I understand >>> that evidence will necessarily be anecdotal, but let's not let that >>> stop us. >>> >>> Derek >>> -- >>> >>> Derek Logan tel: +46 46 222 1443 >>> >>> Associate professor fax: +46 46 222 4692 >>> >>> Molecular Biophysics mob: +46 76 8585 707 >>> Lund University >>> >>> Box 124, Lund, Sweden >>> >>> >>> >> >> -- >> _______________________________ >> >> Dr. Uwe Müller >> BESSY-MX group BESSY GmbH >> Albert-Einstein-Straße-15 >> D-12489 Berlin >> Phone: +49-(0)30-6392 4974 >> Fax : +49-(0)30-6392 4975 >> email: umue@bessy.de >> url : http://www.psf.bessy.de >> >> BESSY GmbH - Mitglied der Leibniz Gemeinschaft >> Vorsitzender des Aufsichtsrates: Prof. Dr. Dr. h.c. mult Joachim >> Treusch >> Geschäftsführer: Prof. Dr. Dr. h.c. Wolfgang Eberhardt, Prof. >> Dr.Eberhard Jaeschke Sitz Berlin, AG Charlottenburg, HRB 14635 > > > -- Jürgen Bosch University of Washington Dept. of Biochemistry, K-426 1705 NE Pacific Street Seattle, WA 98195 Box 357742 Phone: +1-206-616-4510 FAX: +1-206-685-7002 CCP4bb navigationCCP4bb <-- 1999 <-- November 1999 <-- 30 November 1999 |
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