POSITIONAL ISOMERS OF MONOPEGYLATED INTERFERON ALPHA-2A - ISOLATION, CHARACTERIZATION, AND BIOLOGICAL-ACTIVITY

The success of recombinant interferon alpha in the clinic in part is l imited by two properties of the protein: short serum half-life and imm unogenicity. To improve these properties, interferon alpha-2a was conj ugated with polyethylene glycol (PEG-5000). A homogeneous preparation of monopegylated interferon alpha-2a was subjected to vigorous analyti cal and activity characterization. A newly developed ampholyte-free ch romatofocussing-like cation-exchange HPLC method utilizing a sulfoprop yl resin was used to separate the monopegylated protein into 11 specie s. Peptide mapping, sequencing, and mass spectrometric analyses indica ted that these species are positional isomers where each isomer repres ents a single polymer molecule conjugated to one specific lysine resid ue. No species with a modification at the amino terminus was observed. All 11 isomers show antiviral and antiproliferative activities in the same range as the parent monopegylated interferon alpha-2a. (C) 1997 Academic Press.