The N‐and O‐linked carbohydrate chains of human, bovine and porcine plasminogen

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Abstract
The structures of the N‐and O‐glycans of human, bovine and porcine plasminogen were determined by 500‐MHz 1H‐NMR spectroscopy. The N‐glycans of all three species proved to be of the N‐acetyllactosamine type differing from one another with respect to the sialylation and fucosylation patterns. In the N‐glycan of human plasminogen the two antennae are sialylated with N‐acetylneuraminic acid (NeuAc), whereas in the bovine counterpart both branches carry significant amounts of N‐glycolylneuraminic acid (NeuGc). In porcine plasminogen the sialic acid is mainly NeuAc; the Manα1→6 branch, however, is only partially sialylated. In addition, the porcine N‐glycan is fucosylated to about 80% in α1→6 linkage to the GlcNAc‐1 residue. The O‐glycans of the three species possess an identical Galβ1→3GalNAc core which is α2→3 sialylated with NeuAc at Gal. The disialylated form, which is also present in all three species, has an additional NeuAc residue in α2→6 linkage to GalNAc. Mono‐and disialylated forms occur in different molar ratios in the different plasminogens: 80:20 in human, 70:30 in bovine and 50:50 in porcine. This study on the carbohydrate moiety of these three plasminogens reveals species specificity in terms of various types of microheterogeneities.