Pectic acids sulfation

Numerous publications, particularly by Stone [38, 39], describe the induced Cotton effects in dye complexes with acidic polysaccharides such as heparin, chondroitin sulfate, carboxy me thy 1-cellulose, pectic acid and hyaluronic acid [40—42]. Methylene blue is usually used for these investigations, as its metachromasy depends to a high degree on the polysaccharide structure, As an example of a 4-1 linked amino sugar, heparin with methylene blue has a metachromatic absorption maximum of X = 565 nm. It its ORD a trough appears at 587 nm ( 3), and the CD also shows an exciton split with a zero crossover at 578 nm. These observations indicate dipole coupling and a helical arrangement of the bound dye molecules. 

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