Purification and molecular characterization of human fibroblast interferon

Human fibroblast interferon was purified from serum-containing culture medium by a combination of concanavalin A or Blue Dextran Sepharose affinity chromatography with high-performance liquid chromatography to material exhibiting a single band on sodium dodecyl sulfate-polyacrylamide gel electrophoresis. The interferon could be chromatographed and purified at acidic pH in volatile buffers on RP-8, RP-18, cyclohexyl, phenylalkyl, diphenyl, cyanopropyl, and diol supports. A specific activity averaging around 4 × 10⁸ units/mg was found for the pure material with a molecular weight of 20,000–21,000 after 20,000- to 50,000-fold purifications. In some preparations, low activity levels were also found at positions corresponding to 10,000, 17,000–18,000, 35,000, and 40,000 daltons. Amino acid and amino sugar analysis, partial NH₂- and COOH-terminal sequences, and tryptic peptide patterns determined at the picomole level are reported for the purified interferon.