81] Binding of human interferons to immobilized albumin

Abstract

Human interferon bind selectively to albumin immobilized on agarose opened up an entirely new field of study on the intrinsic hydrophobicity of mammalian interferons. The binding of human interferon to albumin directly immobilized on agarose, even at high ionic strength, suggests the presence of nonelectrostatic forces in the interaction. In addition to its hydrophobic interaction with albumin-agarose, fibroblast interferon displays many other binding properties consistent with high intrinsic hydrophobicity. For example, under physiological solvent conditions, it also binds to L-tryptophan, D-tryptophan, L-phenylalanine, and L-tyrosine either immobilized directly to cyanogen bromide-activated agarose or via molecular arms. Ethylene glycol is again required in the eluent for its efficient displacement. Studies with various straightchain hydrocarbons (molecular arms) when immobilized on agarose also establish a hydrophobic nature of binding, for example, (1) the length of the hydrocarbon ligand and strength of interaction are positively correlated, (2) stronger interactions are observed with hydrocarbon ligands terminated with apolar rather than polar head groups, and (3) reversal of binding occurs by use of various hydrophobic solutes.