Hi Something I'd do is try different programs for the indexing to see if you get both choices with any programs - Mosflm & XDS will give you the 44 characteristic lattices and cell parameters by default (so you can easily see if anything like the C2 cell is a straightforward transformation of the triclinic one), other programs will only give you a selection of the "best" choices (by default, anyway).
But you could just be lucky & get two structures from one crystallisation. On 28 Oct 2016, at 14:21, Artem Evdokimov wrote: > Good morning, > > 53 x 2 = 106 > 79 x 2 = 158 > > Awfully close to 156 and 105 in the C-group. Are you sure there is no tricky > twinning or faulty indexing of some sort - in either of these space group > assignments? > > On the other hand, I have seen two different habits and different spacegroups > growing from the same drop. So maybe you are just lucky? > > Artem > www.xtals.org > 'crystals the size of cats, every time' > > > - Cosmic Cats approve of this message > > On Fri, Oct 28, 2016 at 9:13 AM, Sam Tang <samtys0...@gmail.com> wrote: > Dear all > > Sorry for going a bit off-topic in this thread. > May I seek your advice as on whether you have experienced that crystals being > obtained from the same droplet, looking alike under microscope (rod shape) > and in fact growing possibly from a same nuclei, give two space groups after > indexing? > > I recently obtain crystals for a protein (co-crystallized with a nucleic acid > ligand) and collected two datasets from synchrotron. Although these two > crystals are from the same drop, the SG and unit cell dimensions are very > different: > > Xtal1: C121 (156 60 105 90 111 90) (L-test, Pointless shows that there is no > twinning), ~2.5 Angstrom > Xtal2: P1 (53 60 79 106 105 98), ~3 Angstorm > > Would it be possible that the ligand changes the SG of the crystal so that > only one of the forms contains the ligand? > > Any advice is appreciated and thanks a lot in advance for your input. > > Regards > > Sam Tang > Biochemistry Programme, School of Life Sciences, CUHK > > Harry -- Dr Harry Powell Chairman of International Union of Crystallography Commission on Crystallographic Computing Chairman of European Crystallographic Association SIG9 (Crystallographic Computing)
