Dear all I am refining my model (1.8 A) where there is an excess density even after fitting the N-terminal Met. From Edman degradation data, the Met is actually an FME. However, only the density in one chain allows me to confidently place FME, and not for the other chain. The first chain also has a good enough density for me to be able to build all the residues in the protein except the last two at the C-terminus. So, do I model FME for both chains? Thanks. Mohamed