文摘
The fiber protein purified from the pool of nonincorporated viral protein after infection ofcells with adenovirus type 5 exists as two forms separable by reverse-phase HPLC. As determined bymass spectrometry, this heterogeneity results from a difference in one O-linked N-acetylglucosamine(GlcNac). A western blot analysis using a monoclonal antibody directed against the GlcNac motif showedthat only one of the two forms reacted with the antibody, suggesting that one form carries a single GlcNacand the other form has none. The ratio of glycosylated to nonglycosylated forms of fiber, which is about1, is conserved in assembled viruses. After digestion of glycosylated fiber with endoproteinase GluC,isolation of the glycosylated peptide by reverse-phase HPLC, and chemical derivatization usingdimethylamine, the site of glycosylation was located in the fiber shaft at serine 109 by mass spectrometry.Elimination of glycosylation by site-directed mutagenesis of fiber should help to understand the functionof this postranslational modification.