Binding Interaction Between Boronic Acid Derivatives with Monosaccharaides: Effect of Structural Change of Monosaccharaides Upon Binding Using S–V Plots

Abstract

Sugar sensing and continuous monitoring of glucose (CGM) play an important and vital role in controlling diabetes. The present enzyme‐based sugar sensors have their own drawbacks. Problems associated with them have encouraged alternate approaches to design new sensors. Among many, fluorescent intensity change based sensors are drawing more attention. Fluorescence sensors based on boronic acid derivatives are more popular because of their ability to reversibly bind diol‐containing compounds. Here, the binding ability of two boronic acid derivatives, namely 2‐methylphenyl boronic acid (B1) and 3‐methoxyphenyl boronic acid (B2) with mono saccharides (sugars), is under investigation. The sugar concentration is kept nearly 1000 times more than that of boronic acid. The interactions of B1 and B2 with three saccharides (d‐sorbitol, dextrose, and fructose) are studied by absorbance and steady‐state fluorescence. Both B1 and B2 fluorescence is quenched by formation of esters with saccharides. The results of absorbance and fluorescence measurements indicate that the studied sugars can be ordered by their affinity to B1 as: d‐sorbitol > xylose > dextrose and for B2 as: dextrose > xylose > d‐sorbitol. In each case, slope of modified S–V plots is nearly one indicating only a single binding site in boronic acids for sugars.

Investigation of interaction between boronic acids and sugar: effect of structural change of sugars on binding affinity using steady state and time resolved fluorescence spectroscopy and molecular docking

“…The above equation is linear. It was initially obtained by Benesi-Hildebrand for studying absorption; and then used for studying fluorescence [37,38,39,40]. Binding constant K a can be calculated using the graph of (I 0 /ΔI) vs [Q] (K a ¼ intercept/slope).…”

“…A linear variation is observed in the co-efficient which is as shown in Figure 8. The Lineweaver-Burk equation is used to analyze fluorescence data [38]:…”

“…Boronic acids are continuing to gain interest in scaffold designing of sensors for carbohydrate cognition because of their high sugar intrinsic affinity and reversible rapid equilibrium. Even in simple cells, carbohydrates are found to be endogenous and vital in many of the biochemical processes [14,15,16,17,18,19,20,21,22,23,24,25,26,27,28,29,30,31,32,33,34,35,36,37,38,39,40,41,42,43,44,45,46,47]. Also, they are often linked to proteins that affect activity and cell surfaces.…”

“…It has a covalent reaction with 1,2 or 1,3-diols and forms cyclic esters of five or six members in aqueous solution which is a reversible complexation, and that makes it an ideal interaction in designing of sensors [44,45,46,47]. For determining compounds that contain diol, efforts based on interaction of boronic acid and diol are being made to focus on developing fluorometric and colorimetric sensors [11,12,13,14,15,16,17,18]. There are special advantages with fluorescence-based systems which includes -(a) extremely sensitive technique, (b) host system is not damages due to fluorescence measurements, (c) better results due to fluorescence decay time measurements, (d) the information on microenvironment of the molecule and about the structure is obtainable.…”

“…Two esters are produced as a result of diol binding in tetrahedral or trigonal form. Various factors like concentration and nature of buffer, pH of medium, temperature, dihedral angle of diol, the and pKa value of formed ester, influences the process of binding [25,26,27,28,29,30,31,32,33,34,35,36,37,38,39,40,41,42,43,44,45,46,47]. To have a quantitative study of process of binding, calculation of binding constant, here association constant (Ka) is important.…”