Metabolism of Exogenous 1-(14)C-L-Fucose in the Sham and Gamma Irradiated Rat

Abstract : The methylpentose L-fucose (6-deoxy-L-galactose) is one of several sugar constituents of various glycoproteins and mucopolysaccharides. Serum levels of protein-bound L-fucose have been reported to increase in human diabetes and cancer but remain relatively unchanged in animals exposed to lethal doses of ionizing radiation when compared to increases in levels of other protein-bound carbohydrates. This study was performed to obtain information on the degradative pathway of exogenously administered 1-(14)C-L-fucose in the rat. Previous studies suggest that the catabolism of L-fucose in the mammal proceeds by the following pathway: L-fucose to L-fucono-1, 5-lactone to L-fuconate to 2- keto-3-deoxy-L-fuconate (KDF). The fate of KDF, however, has not been elucidated. Evidence obtained in this study suggests that KDF is oxidized to alpha-ketoglutarate with subsequent production of CO2. Examination of the available data indicates that the primary pathway for L-fucose metabolism in the rat proceeds via phosphorylation and formation of GDP-fucose with subsequent incorporation into glycoproteins. It is suggested that the enzymic phosphorylation of L-fucose is the primary determinative influencing metabolism of exogenous L-fucose in the rat.