Dear Keri
I agree with the other views but if you have a protein that bind to itself in a ordered manner I do not believe that you detect it with these methods. Take for example a coil-coil protein that forms an aggregate or rather dimer or trimers. I believe you have used the best method, size exclusion chromatography already. If you continue with size exclusion chromatography try GuHCl or Urea addition to the buffers to get a monomer and use this as a reference. If you do not get a monomer, you probably have a covalent complex. If you do get monmeric protein go on with other additives, detergents, amino acids, glycerol and so on.
Tomas
---