You may be missing a trick by not using metals as crystallisation additives if your best diffraction is only 3.5 Angstroms. Uranium has to be my favourite heavy metal, even if I've solved more structures with Pt and Hg. It gave crystals diffracting to 1.2 A from a protein that otherwise gave no crystals, and kicked off the MAD as MIR idea. In fact the scattering from the uranium atoms was strong enough the structure could be solved by arp-warp just from the heavy atom positions (and this is a 56 kDa protein). As far as I know it's still the largest structure solved by direct methods, if you allow that definition to include actinides. The anomalous is not too shabby either.
On Jan 16, 2014, at 2:18 AM, RHYS GRINTER wrote: > 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
