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Hello Rhys Grinter, hello to the ccp4bb community, I don't necessarily want to advertise here one of the major research topic of Eric Girard and late Richard Kahn lab (my previous lab ;-) ) but... You could maybe try lanthanide complexes ? They are composed by a chemical ligand, which can provide a non-covalent binding to protein surfaces, and a chelated lanthanoid ion, which can ensure a really high phasing power. If they bind to your protein, you should get accurate phases, wether you collect at the LIII absorption edge of the lanthanide concerned (the best) or at higher energy (Se K edge for example...). Maybe someone have some of the lanthanide complexes currently available <http://www.natx-ray.com/products/catalogue_consum_CSM002.html> around you ? If you can't get them before your synchrotron run, I follow Matthew Franklin for the Sulfur-SAD method. Furthermore, I should add the use of cadmium acetate for your soaking solution. Cd2+ ion bind well to glutamate and aspartate residue, but can also be really invasive... Good luck. Best regards. Romain. Le 15/01/2014 18:18, RHYS GRINTER a écrit : > Hello message board, > > My group has some crystals of an interesting protein to take to the synchrotron in a couple of weeks. We won't be able to prepare and crystallise a SelMet derivative during that time period, but we have loads of crystals sitting around. The diffraction isn't great, we see maybe 3.5 at home but might be enough to get over the line. > It will be a very difficult MR target, so we were thinking of soaking so crystals with heavy atomic compounds that we have lying around. I was wondering if people had any suggestions of compounds that people have used successfully for experimental phasing and maybe concentrations to use and soaking time. > > Cheers, > > Rhys