Characterization and Postnatal Evolution of an Endogenous Protein Inhibitor of Intestinal Fucosyl-Transferase Activities

An endogenous protein inhibitor was shown to act in vitro on small intestinal fucosyl-transferase activities. In order to support the hypothesis of a physiological role in vivo for this inhibitor in the regulation of the fucosylation process, we characterized this inhibitor and studied its postnatal development. This inhibitor acts differently upon the enzymes of intestinal fucosylation processes. Among the different organs analyzed, the inhibitor was found only in the intestine and the pancreas. Intestinal inhibitory activity decreased 10 fold between the 7th and the 24th day of rat postnatal development; this decrease was inversely correlated with intestinal fucosyl-transferase activities. Two mechanisms of action by which the inhibitor could exert a physiological regulatory role are discussed.