Spectrophotometric study of the relative affinities of teichoic acid for different metal ions

Spectrophotometric study of the relative affinities of teichoic acid (TA) for Na+, Ca2+, Mg2+, Cd2+, Hg2+, Cu2+ and Pb2+ described on the basis of the disruption of metachromasia of dye 1,9-dimethyl methylene blue (DMMB)-polyanion (TA) system has revealed the following sequence of relative affinities of TA for these metals: Na+ < Ca2+ < or = Mg2+ < Cd2+ < Hg2+ < Cu2+ < Pb2+. Some of the metal ions particularly Pb2+ and Hg2+ have specific interactions with the dye, and induce distinct metachromatic band of the dye even in the absence of the polyanion.