Assessment of glycosaminoglycan-protein linkage tetrasaccharides as acceptors for GalNAc- and GlcNAc-transferases from mouse mastocytoma.
1997 (English)In: Glycoconjugate Journal, ISSN 0282-0080, E-ISSN 1573-4986, Vol. 14, no 6, 737-742 p.Article in journal (Refereed) Published
Two glycosaminoglycan-protein linkage tetrasaccharide-serine compounds, GlcA beta 1-3Gal beta 1-3Gal beta 1-4Xyl beta 1-O-Ser and GlcA beta 1-3Gal(4-O-sulfate)beta 1-3Gal beta 1-4Xyl beta 1-O-Ser, were tested as hexosamine accepters, using UDP-[H-3]GlcNAc and UDP-[H-3]GalNAc as sugar donors, and solubilized mouse mastocytoma microsomes as enzyme source. The nonsulfated Ser-tetrasaccharide was found to function as an acceptor for a GalNAc residue, whereas the Ser-tetrasaccharide containing a sulfated galactose unit was inactive. Characterization of the radio-labelled product by digestion with alpha-N-acetylgalactosaminidase and beta-N-acetylhexosaminidase revealed that the [H-3]GalNAc unit was alpha-linked, as in the product previously synthesized using serum enzymes, and not beta-linked as found in the chondroitin sulfate polymer. Heparan sulfate/heparin biosynthesis could not be primed by either of the two linkage Ser-tetrasaccharides, since no transfer of [H-3]GlcNAc from UDP-[H-3]GlcNAc could be detected. By contrast, transfer of a [H-3]GlcNAc unit to a [GlcA beta 1-4GlcNAca1-4](2)-GlcA beta 1-4-aMan hexasaccharide acceptor used to assay the GlcNAc transferase involved in chain elongation, was readily detected. These results are in agreement with the recent proposal that two different N-acetylglucosaminyl transferases catalyse the biosynthesis of heparan sulfate. Although the mastocytoma system contains both the heparan sulfate/heparin and chondroitin sulfate biosynthetic enzymes the Ser-tetrasaccharides do not seem to fulfil the requirements to serve as accepters for the first HexNAc transfer reactions involved in the formation of these polysaccharides.
Place, publisher, year, edition, pages
1997. Vol. 14, no 6, 737-742 p.
Biosynthesis, GalNAc transferase, GlcNAc transferase, glycosaminoglycan, proteoglycan
IdentifiersURN: urn:nbn:se:uu:diva-52355ISI: A1997XY64800006PubMedID: 9337087OAI: oai:DiVA.org:uu-52355DiVA: diva2:80264