Immunochemical significance of l- and d-fucose derivatives

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Abstract
The hapten activity of methyl ethers of L- and D-fucose, their glycosides, and of other sugars not directly related to fucose, was investigated in the heterologous eel-serum- and Lotus tetragonolobus anti-H(O)-human O erythrocyte-haemagglutination systems. In addition, inhibition by monosaccharides in the eel-serum-human H(O) ovarian-cyst mucoid precipitin system was measured quantitatively for the first time. The relative inhibitory activities of fucose derivatives in the precipitin-inhibition assay did not strictly parallel those found in the haemagglutina-tion test. L-fuco-pyranoside in a-glycosidic linkage was the most active haptenic structure of the L-fucose series in both the eel-serum and Lotus systems. Some changes on the L-fucose molecule at C-2 and C-3 are compatible with high activity and others are not; substitution at C-4 or C-5 led to inactive compounds. Methyl a-glycosidation did not activate O-methylfucoses. The D- and L-enantiomorphs of 3-O-methylfucose were of equal activity in the eel anti-H(O) haemagglutina-tion-inhibition system; equal activities were also found in the precipitation-inhibition system. These findings are contrary to classical concepts of stereospecificity. Similar observations were made with the 2,3-di-O-methylated derivatives. In the Lotus system, significant activation of D-fucose occurred only by O-methylation of C-2. 2 groups of sugars unrelated to fucose showed low to moderate activity in the Lotus system only. These sugars possessed the D-allose configuration and D-glucose derivatives possessing O- or C-methyl groups. A large number of other sugars were inactive in both systems. Explanations for the observed activities and their deviations from accepted theory were attempted by molecular-model studies and by applying conformational theory.