Title :
A novel sialylated N-acetylgalactosamine-containing oligosaccharide is
the major complex-type structure present in Bowes melanoma
tissue plasminogen activator
Abstract :
- We have employed fast atom bombardment mass spectrometry (FAB-MS) to screen the N-linked oligosaccharides of Bowes melanoma tissue plasminogen activator ( mt-PA ), and recombinant t-PAs produced by Chinese hamster ovary cells (rt-PA) and by a gene-enriched melanoma cell line (r mt-PA )
- These studies have confirmed the published structures for rt-PA, but are not in agreement with some of the structures reported for mt-PA
- In the latter glycoprotein we have identified a novel structure as the major oligosaccharide attached to Asn-184 and Asn-448
- This is a biantennary oligosaccharide consisting of a fucosylated trimannosyl core to which are attached two GalNAc(1----4)GlcNAc antennae, one of which carries a sialic acid linked at the 6- position of the GalNAc.
- Minor constituents are sialylated on both or neither antennae
- The sialylated GalNAc moiety is unique in N-linked glycoproteins
- The majority of complex structures in r mt-PA contain N-acetyllactosamine moieties at both the Asn-184 and Asn-448 sites with the novel oligosaccharide occurring as a minor component at the Asn-184 site
- This study demonstrates the power of mass spectrometric strategies based on high-field two-sector FAB-MS for structure elucidations of natural and recombinant glycoproteins