Benzoboroxoles as efficient glycopyranoside-binding agents in physiological conditions: structure and selectivity of complex formation.
In contrast to normal boronic acids, o-hydroxymethyl phenylboronic acid (benzoboroxole) has the capability of complexing glycopyranosides efficiently in neutral water. The measurement of association constants with a panel of model hexopyranosides indicates that the preferred mode of binding is through a cis-3,4-diol, such as that found in galactopyranosides, and mass spectrometric studies support a 1:1 binding stoichiometry. The complexation of glucopyranosides is weaker, and they are bound through their 4,6-diol unit. Although several factors may explain the exceptional carbohydrate-binding behavior of this class of hemiboronic acids, the relatively high Lewis acidity of benzoboroxoles is a likely contributing factor along with subtle factors such as intramolecular hydrogen bonds with other hydroxyl groups in the resulting anionic complex. These results with hexopyranosides suggest that biologically relevant cell-surface oligosaccharides could be targeted in water using oligomeric benzoboroxole receptors.
Bérubé
Marie
M
Department of Chemistry, University of Alberta, Edmonton, Alberta T6G 2G2, Canada.
Dowlut
Meenakshi
M
Hall
Dennis G
DG
D001665:Binding Sites; D001897:Boronic Acids / Q000737:chemistry* / Q000378:metabolism; D002462:Cell Membrane / Q000737:chemistry / Q000378:metabolism; D005690:Galactose / Q000737:chemistry* / Q000378:metabolism; D006860:Hydrogen Bonding; D006863:Hydrogen-Ion Concentration; D009682:Magnetic Resonance Spectroscopy; D009844:Oligosaccharides / Q000737:chemistry / Q000378:metabolism; D012995:Solubility; D013237:Stereoisomerism; D013329:Structure-Activity Relationship; D013816:Thermodynamics; D014867:Water / Q000737:chemistry
D001897:Boronic Acids; D009844:Oligosaccharides; D014867:Water; C010686:benzeneboronic acid; D005690:Galactose