Dear all, I have a 2A structure in C2 space group which is already refined quite well (R=0.194, Rfree=0.229). It is MR solution of the same protein but the crystal form is different. Everything seems to be OK apart from the density on a symmetry axis. The density is not very well defined but it seems to belong to the protein chain. Specifically, to the loop that is ordered in the model structure and fits also into this density. I cannot see any alternative conformation for this region. Does the protein chain on a symmetry axis make a physical sense? Or maybe I have something wrong here?
Karolina -- *********************************** Karolina Michalska, PhD Student Dept. of Crystallography Faculty of Chemistry A. Mickiewicz University ul. Grunwaldzka 6 60-780 Poznan, Poland ***********************************
