Purification and carbohydrate structure of natural murine interferon‐β

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Abstract
Mouse interferon-.beta. (Mu-IFN-.beta.) induced in C-243 cells with Newcastle disease virus was purified in four steps including ammonium sulfate fractionation, DEAE-cellulose, monoclonal Mu-IFN-.beta. antibody affinity and Mono-S cation-exchange chromatographies. Specific activity of the purified Mu-IFN-.beta. ranged over 1.1-1.4 .times. 109 NIH units/mg protein. This preparation was submitted to pronase digestion and gel filtration of Fractogel TSK HW-40. The permethylated and acetylated glycopeptide fraction was analyzed by chemical-ionization (ammonia) mass spectrometry. The major glycopeptide is composed of Gal, Man, GlcNAc and NeuAc with a molar ratio of 2.0:3.6:3.4:0.5. The GLC pattern of methyl derivatives obtained by methanolysis and acetylation of fully methylated glycopeptide identified 2,3,4,6-tetra-O-methylgalactose; 3,4,6-tri-O-methyl-mannose; 2,3,4- and 2,4,6-tri-O-methyl galactose; 2,4,di-O-methyl mannose and 3,6-di-O-methylglucosamine. These results when compared with dat on N-glycans suggest a structure for the carbohydrate moiety of Mu-IFN-.beta. and this is presented.