STUDIES ON THE INTERACTION OF BACTERIAL LIPOPOLYSACCHARIDE WITH CATIONIC DYES BY ABSORBENCY AND FLUORESCENCE SPECTROSCOPY

The interaction of cationic dyes, pinacyanol chloride, acridine orange and safranin O, with Klebsiella O3 lipopolysaccharide has been invest igated by spectrophotometric and spectrofluorometric measurements. A s trong metachromasy is induced by the acidic polysaccharide in pinacyan ol chloride as revealed from the appearance of the blue-shifted absorp tion band at 495 nm from 600 nm. The stoichiometry of the polymer/dye in the metachromatic compound, the thermodynamic parameters of interac tion and the effects of different cosolvents on the stability of compl ex have been studied. Quenching of fluorescence of acridine orange and safranin O by the lipopolysaccharide has also been studied. The chrom otropic property of the biopolymer has been established by the spectra l results. (C) 1997 Elsevier Science S.A.