>I have a small complex, one component is 13 kDa with structure available and the other is 7 kDa, which could not be able to grew crystals after lots of efforts. It grew crystals after methylation and diffracted to 2.3 A, however, I could not be able to solve the structure using the structure of the big component as a template for molecular replacement, and heavy atoms soaking was not successful. I plan to do selenomethionine expression next. Does the methylation change protein structures a lot? otherwise, why does molecular replacement not work? I would much appreciate any idea and suggestions how to solve the structure using the data and the template avaliable.
--- A couple of questions that I would consider in regards to the molecular replacement not working: Is the binding between the proteins 1:1? Does the Matthews coefficient reflect this? MR maybe difficult if you have a number of 7 kDa proteins binding to a 13 kDa protein. Hope that Helps, Sean
