Total chemical synthesis and NMR characterization of the glycopeptide tx5a, a heavily post-translationally modified conotoxin, reveals that the glycan structure is alpha-d-Gal-(13)-alpha-d-GalNAc
| ISSN: | 1432-1033 0014-2956 |
|---|---|
| DOI: | 10.1111/j.1432-1033.2004.04464.x |
| Přístupová URL adresa: | https://explore.openaire.eu/search/publication?articleId=doi_dedup___::900bd28f2c85050c445b1cec4bdf5fa4 https://doi.org/10.1111/j.1432-1033.2004.04464.x |
| Rights: | OPEN |
| Přírůstkové číslo: | edsair.doi.dedup.....900bd28f2c85050c445b1cec4bdf5fa4 |
| Autor: | James Kang, Johan Stenflo, Guo Ping Zhou, Thomas Norberg, Alan C. Rigby, William Low, A. Grey Craig, Karin M Hansson, Julita S. Imperial, Jill Meisenhelder, Baldomero M. Olivera |
| Rok vydání: | 2004 |
| Předmět: |
Glycan
Conus textile Stereochemistry Molecular Sequence Data Disaccharide Peptide Biochemistry chemistry.chemical_compound Conus Conotoxin Threonine Nuclear Magnetic Resonance Biomolecular Chromatography High Pressure Liquid chemistry.chemical_classification biology Hydrolysis biology.organism_classification Glycopeptide Carbohydrate Sequence chemistry Spectrometry Mass Matrix-Assisted Laser Desorption-Ionization biology.protein lipids (amino acids peptides and proteins) Conotoxins Protein Processing Post-Translational |
| Zdroj: | European Journal of Biochemistry. 271:4939-4949 |
| ISSN: | 1432-1033 0014-2956 |
| DOI: | 10.1111/j.1432-1033.2004.04464.x |
| Popis: | The 13-amino acid glycopeptide tx5a (Gla-Cys-Cys-Gla-Asp-Gly-Trp*-Cys-Cys-Thr*-Ala-Ala-Hyp-OH, where Trp* = 6-bromotryptophan and Thr* = Gal-GalNAc-threonine), isolated from Conus textile, causes hyperactivity and spasticity when injected intracerebral ventricularly into mice. It contains nine post-translationally modified residues: four cysteine residues, two gamma-carboxyglutamic acid residues, and one residue each of 6-bromotryptophan, 4-trans-hydroxyproline and glycosylated threonine. The chemical nature of each of these has been determined with the exception of the glycan linkage pattern on threonine and the stereochemistry of the 6-bromotryptophan residue. Previous investigations have demonstrated that tx5a contains a disaccharide composed of N-acetylgalactosamine (GalNAc) and galactose (Gal), but the interresidue linkage was not characterized. We hypothesized that tx5a contained the T-antigen, beta-D-Gal-(1-->3)-alpha-D-GalNAc, one of the most common O-linked glycan structures, identified previously in another Conus glycopeptide, contalukin-G. We therefore utilized the peracetylated form of this glycan attached to Fmoc-threonine in an attempted synthesis. While the result-ing synthetic peptide (Gla-Cys-Cys-Gla-Asp-Gly-Trp*-Cys-Cys-Thr*-Ala-Ala-Hyp-OH, where Trp* =6-bromotryptophan and Thr* = beta-D-Gal-(1-->3)-alpha-D-GalNAc-threonine) and the native peptide had almost identical mass spectra, a comparison of their RP-HPLC chromatograms suggested that the two forms were not identical. Two-dimensional H-1 homonuclear and C-13-H-1 heteronuclear NMR spectroscopy of native tx5a isolated from Conus textile was then used to determine that the glycan present on tx5a indeed is not the aforementioned T-antigen, but rather alpha-D-Gal-(1-->3)-alpha-D-GalNAc. (Less) |
| Databáze: | OpenAIRE |
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