Describe the methods for separating macromolecules on the basis of their size, charge, solubility and molecular affinity?
Gel-filtration chromatography is able to separate molecules on the basis of size (proteins are less soluble in solutions containing high salt than they are in low-salt solutions; so that a mixture of proteins can potentially be separated by addition of large quantities of a salt).
Salting out separates molecules on the basis of solubility (macromolecules interact either with positively or negatively charged stationary phase).
Affinity chromatography separates molecules on the basis of molecular affinity (chromatographic column is set up for which the stationary phase contains a functional group that interacts specifically with the protein of interest).
Electrophoresis that separates molecules on the basis of charge, the charge is transmitted via the ions provided by the buffer.