Interfacial properties of pectinase forming ultrathin films from a saline solution

Pectinase, an enzyme with poor surface activity, was adsorbed from a saline aqueous subphase at the water interface through the salting-out effect. Tensiometry measurements confirmed the formation of stable films at the interface, and surface potential-area isotherms confirmed the orientation of the enzyme dipoles at the interface. Polarization modulation reflection-absorption infrared spectroscopy provided information on the secondary structure of the enzyme, which showed negligible loss of its native conformation, with a majority presence of beta-sheets. We did not observe relevant formation of aggregates by means of cycles of compression-expansion as well as through Brewster Angle Microscopy. The floating enzyme monolayer could be transferred to solid supports as revealed with nanogravimmetry and fluorescence spectroscopy.