SYNTHESIS OF NEOGLYCOPEPTIDES AND ANALYSES OF THEIR BIODISTRIBUTION IN-VIVO TO IDENTIFY TISSUE-SPECIFIC UPTAKE AND NOVEL PUTATIVE MEMBRANE LECTINS

Complex type N-linked oligosaccharides derived from fetuin, fibrinogen and thyroglobulin were coupled to acetyltyrosine affording a series o f neoglycopeptides with retention of terminal structures and the p-ano meric configuration of their reducing end N-acetylglycosamine residue. The neoglycopeptides thus synthesized could be labelled to high speci fic activities with I-125 in the aromatic side chain of tyrosine. Anal ysis of the fate of these neoglycopeptides in conjunction with inhibit ion with asialofetuin and oligosaccharides of defined structure in mic e in vivo revealed the uptake of galactosylated biantennary compound b y kidneys, in addition to the known itinerary of triantennary galactos ylated complex oligosaccharide from fetuin to liver and the galactosyl ated biantennary chain with fucosylation in the core to bone marrows. On the other hand, the agalacto, aglucosamino biantennary chains with and without fucosylation in the core region are taken up by submaxilla ry glands while the conserved trimannosyl core with fucose is primaril y concentrated in stomach tissue. These studies thus define new routes for the uptake of complex N-linked glycans and also subserve to ident ify lectins presumably involved in their recognition.