Nature of the molecular heterogeneity of human leukocyte interferon

The existence of two components of human leukocyte interferon has been recently reported. In the present study, the nature of this molecular heterogeneity was explored by affinity chromatography on immobilized micro- and macroligands, ion-exchange chromatography, and molecular sieving. Chromatography on a series of alkyl-agarose adsorbents shows, for the first time, the intrinsic hydrophobicity of human leukocyte interferon. Additionally, the separation of two interferon components is achieved by use of the alkyl-agarose as well as by the omega-aminoalkyl-agarose adsorbents. Clear-cut separation of the two components was also achieved by chromatography on BSA-CH-Sepharose and on DEAE-Bio Gel A. An important feature of these separations is that they do not require the use of denaturing conditions. The molecular weights of the leukocyte interferon components, as determined on Sephadex G-75, are quite similar or identical, approximately 26,000. Thus, the molecular heterogeneity of human leukocyte interferon can be attributed, at least in part, to differences in the hydrophobicity and ionic properties of its two components.