Interaction of recombinant leukocyte A interferon with lipid monolayers

Abstract

The extent of interaction of recombinant leukocyte A interferon (IFN-[alpha]) with neutral, positively charged and negatively charged phospholipid monomolecular films was studied by measuring its ability, after injection into the subphase, to increase surface pressures exerted by such lipid films. The maximum surface pressure exerted by IFN-[alpha] in the absence of a lipid film (22.6 dyne/cm) was found to be nearly identical to the critical pressure for penetration of IFN-[alpha] into each of the lipid films studied. Thus, for lipid films at surface pressures above this value, there was no measurable penetration by IFN-[alpha]. At lower surface pressure values, injection of IFN-[alpha] into the subphase resulted in an increase in pressure, indicating its penetration into the film. Since the surface pressure exerted by natural and artificial bilayer structures is greater than 22.6 dyne/cm, extrapolation of these observations suggests that IFN-[alpha] would be excluded from the lipid bilayer of liposomes.