Structural analysis of trisialylated biantennary glycans isolated from mouse serum transferrin. Characterization of the sequence Neu5Gc(alpha 2-3)Gal(beta 1-3)[Neu5Gc(alpha 2-6)]GlcNAc(beta 1-2)Man.
Five variants of mouse serum transferrin (mTf, designated mTf-I to mTf-V) with respect to carbohydrate composition have been isolated by DEAE-cellulose chromatography in the following relative percentages: mTf-I: 0.55; mTf-II: 0.79; mTf-III: 71.80; mTf-VI: 21. 90 and mTf-V: 4.96. The primary structures of the major glycans from mTf-III and mTf-IV were determined by methylation analysis and 1H-nuclear magnetic resonance (NMR) spectroscopy. All glycans possessed a common trimannosyl-N,N'-diacetylchitobiose core. From the glycovariant mTf-III two isomers of a conventional biantennary N-acetyllactosamine type were isolated, in which two N-glycolylneuraminic acid (Neu5Gc) residues are linked to galactose either by a (alpha 2-6) or (alpha 2-3) linkage. A subpopulation of this glycovariant contains a fucose residue (alpha 1-6)-linked to GlcNAc-1. The structure of the major glycan found in variant mTf-IV contained an additional Neu5Gc and possessed the following new type of linkage: Neu5Gc(alpha 2-3)Gal(beta 1-3)[Neu5Gc(alpha 2-6)]GlcNAc(beta 1-2 )Man(alpha 1-3). In addition to this glycan, a minor compound contained the same antennae linked to Man(alpha 1-6). In fraction mTf-V, which was found to be very heterogeneous by (1)H NMR analysis, carbohydrate composition and methylation analysis suggested the presence of tri'-antennary glycans sialylated by Neu5Gc alpha-2,6- and alpha-2, 3-linked to the terminal galactose residues. In summary, mTf glycans differed from those of other analyzed mammalian transferrins by the presence of Neu5Gc and by a Neu5Gc(alpha 2-6)GlcNAc linkage in trisialylated biantennary structures, reflecting in mouse liver, a high activity of CMP-Neu5Ac hydroxylase and (alpha 2-6)GlcNAc sialyltransferase.
Laboratoire de Chimie Biologique de l'Université des Sciences et Technologies de Lille, UMR CNRS No. 8576, France.
B
B
Coddeville
E
E
Regoeczi
G
G
Strecker
Y
Y
Plancke
G
G
Spik
D000818:Animals; D002240:Carbohydrate Sequence; D002852:Chromatography, Ion Exchange; D004187:Disaccharides / Q000737:chemistry; D005260:Female; D006020:Glycopeptides / Q000737:chemistry / Q000302:isolation & purification; D009682:Magnetic Resonance Spectroscopy; D008297:Male; D051379:Mice; D008969:Molecular Sequence Data; D015394:Molecular Structure; D019158:N-Acetylneuraminic Acid; D009438:Neuraminic Acids / Q000032:analysis; D011134:Polysaccharides / Q000737:chemistry* / Q000302:isolation & purification; D014168:Transferrin / Q000737:chemistry* / Q000302:isolation & purification
D004187:Disaccharides; D006020:Glycopeptides; D009438:Neuraminic Acids; D011134:Polysaccharides; D014168:Transferrin; C032592:N-glycolylneuraminic acid; C010913:N,N-diacetylchitobiose; D019158:N-Acetylneuraminic Acid