ABSTRACT
I. INTRODUCTION Proteins are themselves surface-active compounds with an amphiphilic nature. The interfacial behavior of proteins is different from that of low-molecularweight amphiphiles with a simple structure, namely, detergents, because pro teins are highly complex polymers made up of a combination of 20 different amino acids (this point is described in detail in Chapter 3 of this book). Nor mally, proteins take on the folded compact structure, in which nonpolar amino acid residues are located in the interior and hydrophilic residues are exposed to molecular surfaces. Since hydrophobic interactions play dominant roles in the adsorption of surfactants to the air-water and oil-water interfaces, such a native structure of proteins should be modified to make full use of the surface activity of proteins [1].
