CONFORMATIONAL-CHANGES OF PROTEINS AT AN INTERFACE INDUCED BY A SUPPORTED PLANAR PHOSPHATIDIC-ACID MONOLAYER

Conformational changes of two types of proteins, water-soluble protein s (BSA and myoglobin) and membrane-associated protein (cytochrome c), induced by a negatively charged supported planar phospholipid monolaye r were studied. The water-soluble proteins lost most of their ordered secondary structure and formed a random conformation in the initial st age of adsorption, and but in the later stage they retained more of th e alpha-helical structure which was their main native secondary struct ure in solution. The membrane-associated protein, cytochrome c, showed a different conformational change in the adsorption process. In the i nitial stage, it showed an increase in beta-structures but not random coils. In the later stage, it contained more alpha-helixes than that i n solution.