Dear Sangheon, you don't say which cubic space group you tried, perhaps you tried the wrong one? Did Pointless indicate a clear preference? Between P23 and P213 for instance you can tell by systematic absences along h (if they were collected ok), but between I23 and I213 the only option is to try both and see if one or the other leads to a good solution. In any case, in principle having P21 with beta near 90 and a nearly equal to b and c is rare, but possible. Greetings, Mark
Mark J van Raaij Lab 20B Dpto de Estructura de Macromoleculas Centro Nacional de Biotecnologia - CSIC c/Darwin 3 E-28049 Madrid, Spain tel. (+34) 91 585 4616 http://www.cnb.csic.es/~mjvanraaij On 25 Oct 2013, at 02:55, 유상헌 wrote: > Hi everyone, > > Recently I’ve got a protein crystal and I did indexing and scaling with a > cubic space group (unit cell 104.115 104.115 104.115 90.0 90.0 90.0). But a > Rmerge value was too high (around 0.5-0.6). So, I tried lower symmetry space > groups and I successfully solved the structure with a space group P21 > (Rwork/Rfree: 0.22/0.27). However, there was one strange fact. The unit cell > of the P21 was 104.209 104.225 104.254 90.000 89.967 90.000. I’m confused > with this fact that a, b, and c of the unit cell are almost same, and in > addition, the beta angle is too close to 90. I didn’t do refinement with a > twin option. So, is the space group correct? Is there anyone who know this > case? > > Thanks, > > Sangheon Yu > Rm. 1053 Bldg. 200 > School of Agricultural Biotechnology > College of Agriculture & Life Sciences > Seoul National University > Seoul 151-921, KOREA > >
