Synthesis of β-(1→6)-linked N-acetyl-d-glucosamine oligosaccharide substrates and their hydrolysis by Dispersin B

Anikó Fekete, Anikó Borbás, Gyöngyi Gyémánt, Lili Kandra, Erika Fazekas, Narayanan Ramasubbu, Sándor Antus

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Abstract

Dispersin B (DspB) from Aggregatibacter actinomycetemcomitans is a β-hexosaminidase exhibiting biofilm detachment activity. A series of β-(1→6)-linked N-acetyl-d-glucosamine thiophenyl glycosides with degree of polymerisation (DP) of 2, 3, 4 and 5 were synthesized, and substrate specificity of DspB was studied on the obtained oligosaccharides. For oligomer synthesis a 1+2, 2+2, 1+4 coupling strategy was applied, using bromo-sugars as glycosyl donors. The formation of 1,2-trans interglycosidic bond has been ensured by 2-phtalimido protecting group; chloroacetyl group was installed to mask temporarily the 6-hydroxyl and acetate esters were applied as permanent protecting groups. Enzymatic studies revealed that DP of the GlcNAc oligomers strongly affected the hydrolysis rate, and the hydrolytic activity of DspB on the tetramer and pentamer have been found to be approximately 10-fold higher than that of the dimer. This fact indicates that four units are required for a strong binding at the active centre of DspB. The role of aromatic amino acids W237, Y187 and Y278 in substrate specificity and catalysis was also examined using mutant enzymes.

Original languageEnglish
Pages (from-to)1445-1453
Number of pages9
JournalCarbohydrate Research
Volume346
Issue number12
DOIs
Publication statusPublished - Sep 6 2011

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Keywords

  • Biofilm
  • Dispersin B
  • Mutation
  • Substrate specificity
  • Synthesis
  • β-(1→6)-Oligoglucosamine

ASJC Scopus subject areas

  • Analytical Chemistry
  • Biochemistry
  • Organic Chemistry

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