Synthesis of 4-methylumbelliferyl α-d-mannopyranosyl-(1→6)-β-d-mannopyranoside and development of a coupled fluorescent assay for GH125 exo-α-1,6-mannosidases.

Autor: Deng L; Department of Chemistry, Simon Fraser University, 8888 University Drive, Burnaby, British Columbia V5A 1S6, Canada., Tsybina P, Gregg KJ, Mosi R, Zandberg WF, Boraston AB, Vocadlo DJ
Jazyk: angličtina
Zdroj: Bioorganic & medicinal chemistry [Bioorg Med Chem] 2013 Aug 15; Vol. 21 (16), pp. 4839-45. Date of Electronic Publication: 2013 Jun 11.
DOI: 10.1016/j.bmc.2013.05.062
Abstrakt: Certain bacterial pathogens possess a repertoire of carbohydrate processing enzymes that process host N-linked glycans and many of these enzymes are required for full virulence of harmful human pathogens such as Clostridium perfringens and Streptococcus pneumoniae. One bacterial carbohydrate processing enzyme that has been studied is the pneumococcal virulence factor SpGH125 from S. pneumoniae and its homologue, CpGH125, from C. perfringens. These exo-α-1,6-mannosidases from glycoside hydrolase family 125 show poor activity toward aryl α-mannopyranosides. To circumvent this problem, we describe a convenient synthesis of the fluorogenic disaccharide substrate 4-methylumbelliferone α-d-mannopyranosyl-(1→6)-β-d-mannopyranoside. We show this substrate can be used in a coupled fluorescent assay by using β-mannosidases from either Cellulomonas fimi or Helix pomatia as the coupling enzyme. We find that this disaccharide substrate is processed much more efficiently than aryl α-mannopyranosides by CpGH125, most likely because inclusion of the second mannose residue makes this substrate more like the natural host glycan substrates of this enzyme, which enables it to bind better. Using this sensitive coupled assay, the detailed characterization of these metal-independent exo-α-mannosidases GH125 enzymes should be possible, as should screening chemical libraries for inhibitors of these virulence factors.
(Copyright © 2013 Elsevier Ltd. All rights reserved.)
Databáze: MEDLINE
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