Adsorbed films of bovine serum albumin: tensions at air-water surfaces and paraffin-water interfaces.

Abstract

Abstract Using the pendant-drop method, the interfacial tension between n-octadecane and aqueous solutions of bovine serum albumin reached constant values after about 30 min, and became independent of protein concentration above about 0.025%. At low ionic strength there is a minimum in the interfacial tension in the isoelectric region whereas at higher ionic strengths there is a tendency for a maximum to occur in this pH region. The addition of octadecylamine to the n-octadecane decreases considerably the interfacial tension against water both in the presence and absence of bovine serum albumin. The entropy change per unit area of interface goes through a sharp maximum with increasing concentration of bovine serum albumin. The compressibilities of the interfacial bovine serum albumin films as obtained from decreasing the size of the drop increases sharply at a film pressure of about 22 dynes/cm.