Optical rotatory dispersion of mucopolysaccharides and mucopolysaccharide–dye complexes

Abstract

Abstract Anomalous optical rotatory dispersion (ORD) is induced in symmetric dyes when bound in metachromatic complexes with chondroitin sulfates (ChS) and kerato sulfate (KS) from mammalian and shark origin as well as with heparin (H) providing inference that secondary structures exist in these biopolymers. The induced rotation occurs in the absorption band of the bound dye and differs in shape and/or spectral position from the classical Cotton effect seen with single optically active chromophores. The AO:ChS complex has an induced ORD curve similar to that of the exciton band of a helical polymer. Strength of the induced rotations with methylene blue increases with the degree of metachromasy of the 1:1 complex. The sense of the MB Cotton effects may depend upon the conformations of the repeating dimeric units, since MB complexes with ChS (alternating 1‐3,1‐4 β‐glycosides) give (+) effects while MB:H (1‐4 α‐glycosides) have (−) effects in the γ band region. Preliminary evidence for the occurrence of Cotton effects with the mucopolysaccharides themselves in the ultraviolet region was obtained. The sign of the Cotton effect for ChS‐C is (−), trough about 45.9 kK., crossover about 48.8 kK. whereas that for H is (+), peak about 50.4 kK.