Dataset Information

Comparative rates of transfer of N-acetylneuraminic acid to acceptors bearing one or more Gal(beta 1-4)GlcNAc terminus by the Gal(beta 1-4)GlcNAc(NeuAc-Gal) (alpha 2-6)-sialyltransferase from embryonic chicken liver. Utilization of oligosaccharides as acceptors in sialyltransferase assays.

ABSTRACT: Using a number of branched and unbranched oligosaccharides, glycoproteins and artificial glycoproteins bearing Gal(beta 1-4)GlcNAc-R termini as acceptors (where R represents H, oligosaccharide, oligosaccharide-protein or fatty acid-protein), the comparative rates of transfer of NeuAc by the Gal(beta 1-4)GlcNAc(NeuAc-Gal) (alpha 2-6)-sialyltransferase of embryonic chicken liver were determined. Acceptor substrates were utilized at levels approximating physiological, near the Km value of the best acceptor, desialylated alpha 1 acid glycoprotein. The sialyltransferase has a marked preference for multi-branched acceptors. From the specificity data, it is concluded that the enzyme binds at least two Gal(beta 1-4)GlcNAc termini of an acceptor molecule, and that the relative orientation of the branches is an important factor determining the rate of catalysis by the enzyme. The use of oligosaccharides as acceptors to study sialyltransferase catalyses is emphasized. Results are discussed in the context of the mode of assembly of sialoside termini of known glycoprotein structures in vivo.

SUBMITTER: Bendiak B

PROVIDER: S-EPMC1152116 | biostudies-other | 1983 Jul

REPOSITORIES: biostudies-other

ACCESS DATA

Similar Datasets

Project description:The protozoan parasite, Trypanosoma cruzi, the etiologic agent of Chagas disease (ChD), has a cell surface covered by immunogenic glycoconjugates. One of the immunodominant glycotopes, the trisaccharide Gal?(1,3)Gal?(1,4)GlcNAc?, is expressed on glycosylphosphatidylinositol-anchored mucins of the infective trypomastigote stage of T. cruzi and triggers high levels of protective anti-?-Gal antibodies (Abs) in infected individuals. Here, we have efficiently synthesized the mercaptopropyl glycoside of that glycotope and conjugated it to maleimide-derivatized bovine serum albumin (BSA). Chemiluminescent-enzyme-linked immunosorbent assay revealed that Gal?(1,3)Gal?(1,4)GlcNAc?-BSA is recognized by purified anti-?-Gal Abs from chronic ChD patients ?230-fold more strongly than by anti-?-Gal Abs from sera of healthy individuals (NHS anti-?-Gal). Similarly, the pooled sera of chronic Chagas disease patients (ChHSP) recognized Gal?(1,3)Gal?(1,4)GlcNAc? ?20-fold more strongly than pooled NHS. In contrast, the underlying disaccharide Gal?(1,4)GlcNAc? and the monosaccharide GlcNAc? or GlcNAc? conjugated to BSA are poorly or not recognized by purified anti-?-Gal Abs or sera from Chagasic patients or healthy individuals. Our results highlight the importance of the terminal Gal? moiety for recognition by Ch anti-?-Gal Abs and the lack of Abs against nonself Gal?(1,4)GlcNAc? and GlcNAc? glycotopes. The substantial difference in binding of Ch vs. NHS anti-?-Gal Abs to Gal?(1,3)Gal?(1,4)GlcNAc?-BSA suggests that this neoglycoprotein (NGP) might be suitable for experimental vaccination. To this end, the Gal?(1,3)Gal?(1,4)GlcNAc?-BSA NGP was then used to immunize ?1,3-galactosyltransferase-knockout mice, which produced antibody titers 40-fold higher as compared with pre-immunization titers. Taken together, our results indicate that the synthetic Gal?(1,3)Gal?(1,4)GlcNAc? glycotope coupled to a carrier protein could be a potential diagnostic and vaccine candidate for ChD.

Dataset Information

Comparative rates of transfer of N-acetylneuraminic acid to acceptors bearing one or more Gal(beta 1-4)GlcNAc terminus by the Gal(beta 1-4)GlcNAc(NeuAc-Gal) (alpha 2-6)-sialyltransferase from embryonic chicken liver. Utilization of oligosaccharides as acceptors in sialyltransferase assays.

Similar Datasets

OmicsDI is part of the ELIXIR infrastructure

Tweets