CONFORMATIONS OF HYDROPHOBIC POLYELECTROLYTES.

Recent studies on the (hypercoiled) compact conformation and the pH-induced conformational transition to the extended coil of the hydrophobic poly(acids or bases), which have been well used in industrial and medical circles, are summarized, especially on the basis of our studies on poly( alpha -alkyl acrylic acids) and maleic acid copolymers with hydrophobic aromatic monomers. The stability of the compact conformation and values of various thermodynamic parameters of the transition of the hydrophobic polyelectrolytes suggest the importance of hydrophobic interaction among the side chains to form the compact conformation. Characterization of various physicochemical methods, including **1H-NMR measurements, gives a model of the compact conformation with a more expanded structure than in globular proteins, a free-draining property of the solvent, the conformation fluctuation, etc.