Optical rotations Galactans

Several physicochemical methods of investigation, such as measurement of optical rotation (including optical rotation dispersion and circular dichroism) rheological methods, and X-ray analysis of fibers and films, have played a very important role for determination of conformations of galactan molecules and characterization of their supramolecular structures.8,19 As mentioned in Section I, only physicochemical methods used for determination of primary structures of polysaccharides are considered in this chapter. 

Homogeneous D-galactan sulphates have been isolated from the testes of the tunicates Halocynthia roretzi and Styela plicata. The results of optical rotation, i.r.spectroscopy, and acid hydrolysis studies suggest that the polysaccharides have repeating sequences of a-L-galactopyranosyl 4-sulphate and a-L-galactopyranosyl 6(or 3)-sulphate. 

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