HUMAN-MILK FUCOSYL-TRANSFERASE AND ALPHA-L-FUCOSIDASE ACTIVITIES CHANGE DURING THE COURSE OF LACTATION

Human milk is rich in fucosylated oligosaccharides and other glycoconjugates, some of which affect interactions between pathogens and host cell surface. Two types of enzymes, fucosyltransferase and alpha-L-fucosidase, involved in the biosynthesis and degradation of these compounds, were analyzed in random samples of human milk from healthy donors. In mature milk (days 52 to 78), the individual variability for fucosyltransferase was twice that of fucosidase. The activities of both enzymes were observed to change over the course of lactation from day 3 to day 370. alpha-Fucosyltransferase activity was greatest during the first 30 days of lactation and declined significantly between 30 and 100 days. From day 100, fucosyltransferase activity remained nearly constant. Fucosidase activity was high at the onset of lactation followed by a precipitous decline, reaching a nadir by the second week. After the fourth week, the alpha-L-fucosidase activity increased in direct proportion to the length of lactation. The possible relationship of these enzymes to the fucosyloligosaccharide content of human milk are discussed.