Hi all, We have been trying to solve a structure of protein-protein complexes using 3.1A data (one of the proteins is of 120kDa whereas the other is of 20kDa). The structure of smaller protein is known (individually-100% sequence identity) whereas the bigger protein does not share more than 10% sequence identity with the similar proteins solved from other sources.
Due to some problem in getting Seleno-labelled protein, we have also been trying to use molecular replacement (MR) to solve the structure. We want to find out the correct position of smaller protein using MR and then plan to extend the phases to the whole asymmetric unit (we hope it could be done but not sure). We are more or less sure about the fold of bigger protein and expect it to be similar to the other known related structures. In one of the solution obtained using phaser, the map looks really good, but this solution doesn't provide good packing of the complex inside the unit cell. Due to low scattering contribution of the smaller protein, we are unable to refine any possible solutions using REFMAC. We welcome any kind of suggestions in this regard. Thanking you in advance. Joe
