Hi Derek We have had success with iodine - 20 seconds soak.
J Derek Logan <[EMAIL PROTECTED]> 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: [EMAIL PROTECTED] >> 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 -- Professor James Whisstock NHMRC Principal Research Fellow / Monash University Senior Logan fellow Department of Biochemistry and Molecular Biology Monash University, Clayton Campus, PO Box 13d, VIC, 3800, Australia +613 9905 3747 (Phone) +613 9905 4699 (Fax) +61 418 170 585 (Mobile)
