Also you can treat your SeMET as heavy atom derivative with your native dataset. J?rgen
...................... J?rgen Bosch Johns Hopkins University Bloomberg School of Public Health Department of Biochemistry & Molecular Biology Johns Hopkins Malaria Research Institute 615 North Wolfe Street<x-apple-data-detectors://4>, W8708 Baltimore, MD 21205<x-apple-data-detectors://5/0> Office: +1-410-614-4742<tel:%2B1-410-614-4742> Lab: +1-410-614-4894<tel:%2B1-410-614-4894> Fax: +1-410-955-2926<tel:%2B1-410-955-2926> http://lupo.jhsph.edu<http://lupo.jhsph.edu/> On May 18, 2015, at 13:37, Mark J van Raaij <mjvanra...@cnb.csic.es<mailto:mjvanra...@cnb.csic.es>> wrote: Hi Isa, don't discard SeMet too rapidly if there are few Mets, modern beamlines, high-redundancy data collection techniques, and processing and phasing programs can extract and use small anomalous signal to get structures even if there are less SeMets than generally accepted by the "rule of thumb". Especially if you can rotate around more than one axis or merge data from different crystals. And even if the signal is not good enough and you then need additional phasing, the SeMet anomalous maps may be useful in tracing. If you have Cys, try Hg compounds, my favourite is methylmercury chloride. As it binds covalently, even if it precipitates in your drop, you may just get just enough soluble to react. We usually add a few grains of the mercury compound to the reservoir, mix, cover and let equilibrate with the drop for a few hours or overnight, then add a ul of the reservoir to the drop and fish crystals after different incubation times. Greetings, Mark Mark J van Raaij Dpto de Estructura de Macromoleculas Centro Nacional de Biotecnologia - CSIC c/Darwin 3 E-28049 Madrid, Spain tel. (+34) 91 585 4616 http://www.cnb.csic.es/~mjvanraaij On 18 May 2015, at 11:42, isabelle Lucet wrote: Hi All, We recently obtained a native data set to 2.8A. With no molecular replacement available we are now moving to heavy atom (not enough methionine coverage for seleno-met). Unfortunately crystals grow is in 1.4 Na/K H phosphate pH 8 and we do not have much room for improvement. Any literature you could point to or experience with for example gadolinium complexes, co-crystallization, soaking in phosphate buffer? Are we better off just focusing on class B metals? Thanks for your advise. Kind Regards, Isa ______________________________________________________________________ The information in this email is confidential and intended solely for the addressee. You must not disclose, forward, print or use it without the permission of the sender. ______________________________________________________________________
