The use of micro-scale column chromatography and affinity immunoelectrophoresis with group-specific sorbents allows studying some physical and chemical properties of protein molecules. A comparison of properties of soluble and membrane brain amino-peptidases carried out by means of micro-scale phenyl-sepharose and ConA-sepharose column chromatography shows that the membrane-bound aminopeptidase is a glycoprotein which possesses a high capacity to hydrophobic interactions. Soluble forms of aminopeptidase do not interact with ConA or phenyl residues. The crossed affinity immunoelectrophoresis in the presence of phenyl-sepharose also shows the presence of hydrophobic domains on the surface of glial fibrillary acidic protein molecules. The both approaches may be useful to predict conditions for large-scale affinity chromatography methods of protein and enzyme purification.