Thank you for the suggestions. The data resolution is 1.9 so i can try different heavy atoms techniques ... anyway i am really puzzled by the peculiar assembly in the crystal and on the possible causes... does anyone know about similar cases? mario
> > Mario, > beside what you were mentioning, I would definitely try a quick soak > (10-30 seconds) of the crystals in cryo conditions supplemented with > halides such as NaBr, or NaI, at pretty high concentrations (say 0.5 M), > then directly freezing without backsoak. > If the crystals survive the treatment, with that amount of mols per unit > cells and surely some good NCS, you should be able to phase pretty easily. > Well, of course SeMet would be the other option... > ciao, > s > > On Sep 30, 2010, at 1:54 PM, Mario Milani wrote: > >> Dear all, >> i have a 30 kDa protein that crystallize so far in three different >> conditions but with the same space group. It initially looks like >> tetragonal (I4, a=141, b=141, c=208) and then results triclinic (P1, >> a=141, b=141 c=144, alpha=119, beta=119, gamma=90), hosting about 24 >> mol. in the unit cell. Other data: self rotation shows the presence of 4 >> peaks with chi=180; molecular replacement shows the presence of a >> pseudo-translation peak; DLS made at protein concentration close to >> crystal growth conditions shows a Rh compatible with something like a >> tetramer with low polydispersity (about 15%). Do you have any experience >> with similar asymmetric associations? Do you have any suggestions, >> beside the addition of ligands to the crystal growth conditions, in >> order to get a simpler crystallographic assembly? I have some models >> (with sequence identity less than 25%) in order to try MR but all trials >> so far did not solve the structure (using balbes, molrep, phaser and >> epmr). Any suggestion is welcome. >> Thank you, >> >> Mario Milani > > > -- > Sebastiano Pasqualato, PhD > IFOM-IEO Campus > Dipartimento di Oncologia Sperimentale > Istituto Europeo di Oncologia > via Adamello, 16 > 20139 - Milano > Italy > > tel +39 02 9437 5094 > fax +39 02 9437 5990 > >
