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Hey Jenny, > > The protein is only 90 residues ( 10kDa), so looks to me the cell size > is a little big. If your spacegroup is really R32 this means around 3 molecules per asymmetric unit. This is not unusual. > > I heard that it's quite tricky for R32 and I wondered what's that. R32 has z=18 giving you 3*18=54 Molecules per unit cell. As far as I understand molecular replacement this gives you a bad signal to noise ratio for the search. Additionally your molecule is very small. If there is just a small conformational change between the wt crystal form and your R32 crystal form this will corrupt your search model giving you a even worse signal. > If MR doesn't succeed, does this mean, the new mutant protein is > very different from the wild type? Not necessarily. See above. Why not try SeMet or a good old heavy atom derivate? best regards Christian
