Binding interaction between 2-methoxy-5-fluoro phenyl boronic acid and sugars: Effect of structural change of sugars on binding affinity

The binding interaction of 2-methoxy-5-fluoro phenyl boronic acid with various sugars like dextrose, arabinose, xylose, sucrose, and lactose is investigated in aqueous medium at pH 7.4 using the fluorescence spectroscopic method. Fluorescence intensity is reduced upon addition of sugars. The change in the intensity is attributed to breaking of intramolecular hydrogen bonding and to the lesser stability of boronic ester. Data are analyzed using the Benesi-Hildebrand equation and Lineweaver-Burk equation. The estimated binding constants are greater in mono sugars arabinose and xylose. The fact that a structural change in sugar arises due to mutarotation plays a major role in binding interactions. The furanose form of the sugar is found to be more favoured for binding. (author)