Alpha 2,3- and alpha 2,6-sialylation of human skim milk glycoproteins during milk maturation

Human milk is a source of glycoconjugates,sialylated forms of which enrich the newborn immature immune system and are crucial for their proper development and well-being. here,we analyzed the expression of α2,3-/α2,6-sialylated glycotopes on skim milk glycoproteins over lactation. milk samples were analyzed by lectin-blotting using α2,3- and α2,6- sialic acid specific maackia amurensis (maa) and sambucus nigra (sna) lectins and sialyl- and asialyl-t antigen specific artocarpus integrifolia (jacalin) and arachis hypogaea (pna) lectins. the reactivities of maa,sna,jacalin and pna with milk glycoproteins showed that they are heavily decorated with α2,3-/α2,6-linked sialic acid and sialyl-t antigen and to a lesser degree with asialyl-t antigen. despite individual differences of particular glycoproteins,a sharp and significant decline of α2,6-sialylated glycotopes and sialyl-t antigens and a weaker but significant decrease of α2,3-sialylated glycotopes and asialyl-t antigens on milk glycoproteins during milk maturation was observed. the expression of α2,3-/α2,6-sialylated glycotopes,sialyl- and asialyl-t antigens corresponds to milk maturation but differs in relation to the analyzed glycoprotein. sialylated milk glycoproteins are considered as a part of innate immunity provided to neonates. further investigations are needed to understand if they may be useful in milk banking to control the biochemical quality of milk. © 2017 faculty of health and social sciences,university of south bohemia in ceske budejovice