STRUCTURES OF THE SUGAR CHAINS OF RECOMBINANT MACROPHAGE-COLONY-STIMULATING FACTOR PRODUCED IN CHINESE-HAMSTER OVARY CELLS

The structures of the N- and O-linked sugar chains of recombinant huma n macrophage colony-stimulating factor (rhM-CSF) from Chinese hamster ovary (CHO) cells were studied. rhM-CSF is a homodimeric glycoprotein. Sugar composition analysis revealed that rhM-CSF contained 4.1 mol N- acetylgalactosamine, 10.3 mol N-acetylglucosamine, 5.0 mol mannose, 10 .0 mol galactose, 1.4 mol fucose, and 11.8 mol sialic acid per mol of the monomer, The N- and O-linked sugar chains liberated by hydrazinoly sis were N-acetylated, and the reducing-end sugar residues were tagged with 2-aminopyridine. The pyridylamino (PA-) sugar chains thus obtain ed were purified by HPLC, The structures of the PA-sugar chains were a nalyzed by a combination of reversed-phase and size-fractionation HPLC , and exoglycosidase digestions, from which the structures of the rhM- CSF sugar chains were estimated to be as follows: monosialo biantennar y sugar chain (9 mol%), monosialo fucosylbiantennary sugar chain (10 m ol%), disialo biantennary sugar chain (30 mol%), disialo fucosylbiante nnary sugar chain (28 mol%), disialo triantennary sugar chain (7 mol%) , trisialo triantennary sugar chain (11 mol%), and trisialo fucosyltri antennary sugar chain (5 mol%) for the N-linked sugar chains, and asia lo (27 mol%), monosialo (51 mol%), and disialo (22 mol%) Gal beta 1-3G alNAc for the O-linked sugar chains, Sialic acid residues were linked to the N-linked sugar chains through an alpha 2-3 linkage.