Porcine fibrinogen glycopeptides: substrates for detecting endo-beta-N-acetylglucosaminidases F2 and F3(1)

Two different glycopeptides were isolated in high yield from a thermolytic digest of porcine fibrinogen. Edman analysis established their sequences as Val-Glu-Asn(CHO)-Lys and Val-Gly-Glu-Asn(CHO)-Arg. These sequences are nearly identical to the two human fibrinogen glycopeptides, Val-Glu-Asn(CHO)-Lys (gamma-chain), and Met-Gly-Glu-Asn(CHO)-Arg (beta-chain). The predominant carbohydrate moiety of both asialoglycopeptides was a biantennary oligosaccharide with a core alpha(1-->6)-linked fucose as reported earlier (Da Silva et al. (1994) Arch. Biochem. Biophys. 312, 151-157). Both glycopeptides can be dansylated and used as sensitive substrates for Flavobacterium meningosepticum endo-beta-N-acetylglucosaminidases F2 and F3. Porcine fibrinogen represents the best source for substrates with this oligosaccharide type that can be reliably produced in multimicromole quantities.