It is entirely possible (fairly common) to have two different crystals in one drop. If the habits are the same I'd expect the same cell, but that doesn't have to be the case. Likewise, if the habits are different I'd expect different cells, but again that is not necessarily the case.
bert ________________________________ From: CCP4 bulletin board <CCP4BB@JISCMAIL.AC.UK> on behalf of Sam Tang <samtys0...@gmail.com> Sent: 28 October 2016 14:13 To: CCP4BB@JISCMAIL.AC.UK Subject: [ccp4bb] Two SGs in one droplet? 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
