The immunochemistry of λ-type carrageenans from certain red algae

An antibody preparation directed against a structural feature associated with 6-sulphate groups was used to probe structural relations among certain λ-type carrageenans. Immunochemical and chemical differences are described between the KCl-soluble carrageenans from tetrasporic algal plants of Gigartina corymbifera, Gigartina sp. from San Francisco Bay, Petrocelis middendorfii, Iridaea cordata, Rhodoglossum californicum, and Chondrus crispus. The differences in immunochemical reactivity of the Gigartina and Petrocelis carrageenans relative to the homologous antigen ( Chondrus crispus λ-carrageenan) are attributed to the lower content of 6-sulphate groups on the 4-linked residues in the former carrageenans. Both the immunochemical and chemical data suggest that the Gigartina and Petrocelis carrageenans are largely č-like in structure but do contain λ-like features. The i.r. spectrum of the Petrocelis carrageenan differs from that of the Gigartina carrageenans. The carrageenans from I. cordata and R. californicum differ to a lesser degree from Chondrus crispus λ-type carrageenan. These differences cannot be accounted for by differences in the levels of 6-sulphate groups. Some other structural feature, as yet unidentified, is responsible for the discrepancy in the immunochemical reactivity of these carrageenans to the anti-λ-carrageenan.