Use of metachromatic shift as a method to study interaction between lipopolysaccharides of Mesorhizobium strains and chickpea lectin like protein

Nature of charge distribution of specific and non-specific Mesorhizobium lipopolysaccharide (LPS) has been studied by its interaction with acridine orange (AO) in phosphate buffer (0.1mM, pH 7.2). It was found that the cationic dye AO showed a decrease in absorption maxima of the dye at 490nm upon addition of LPS till the L/D ratio of 30.0 and on further addition it gave rise to metachromatic band at 460nm only for specific Mesorhizobium strain IC 59 whereas non-specific Mesorhizobium strain TAL 1000 showed only a decrease in absorbance at 490nm. This observation indicated that the charge distributions of LPS from two Mesorhizobium strains are different. Displacement of metachromatic complex was seen on adding increasing concentration of Cicer arietinum L root and seed protein to the mixture of AO and LPS.