The chemistry and immunochemistry of carrageenans from Eucheuma and related algal species

Carrageenans from several species of Eucheuma have been fractionated into KCI-soluble and KCI-insoluble fractions and analyzed by the usual chemical procedures. An anti-K-carrageenan, the reactivity of which is directed to K-structures (i.e., 3-linked galactose 4-sulphate, and 4-linked 3,6-anhydrogalactose) was used to analyze these carrageenans immunochemically. The antibody preparation shows only a small amount of cross-reactivity with i-type carrageenans and thus could be used to distinguish K- and i-type carrageenans, the latter having an index of homology of less than 0.2. A comparison of chemical and immunochemical data yielded further information as to the nature of the carrageenan-anti-carrageenan interaction, as well as elucidating the finer structure of carrageenans.