Carbohydrate structures of beta-trace protein from human cerebrospinal fluid: evidence for "brain-type" N-glycosylation.
The carbohydrate structures of beta-trace protein from human cerebrospinal fluid have been elucidated. This protein carries exclusively N-linked oligosaccharides at two sites (Asn29 and Asn56). Enzymatically released N-glycans were studied by compositional and methylation analyses, high-pH anion-exchange chromatography, and liquid secondary ion mass spectrometry. All glycans were found to be of the complex type, and most (90%) of them were biantennary with no (40%), one (40%), or two (20%) N-acetylneuraminic acid residues. The rest were triantennary chains or biantennary chains with intact or truncated lactosamine repeats. The innermost N-acetylglucosamine residues of nearly all structures were found to be alpha 1,6-fucosylated. Peripheral fucose (about 20% alpha 1,3-linked to N-acetylglucosamine) was also detected. Seventy percent of the oligosaccharides contained a bisecting N-acetylglucosamine. Especially in the neutral, but also in the monosialylated oligosaccharide fractions, many incomplete antennae consisting of N-acetylglucosamine only were present. At least 20 different N-glycans were identified. Analysis of the site-specific glycosylation patterns at Asn29 and Asn56 revealed only minor differences. According to the structural features (a high degree of fucosylation, high amounts of bisecting N-acetylglucosamine, as well as terminal N-acetylglucosamine and galactose residues, and significant amounts of N-acetylneuraminic acid in alpha 2,3 linkage), this protein can be classified as "brain-type" glycosylated.
Hoffmann
A
A
Department of Neurology, Medizinische Hochschule Hannover, Germany.
Nimtz
M
M
Wurster
U
U
Conradt
H S
HS
D000117:Acetylglucosamine / Q000032:analysis; D000581:Amidohydrolases / Q000378:metabolism; D001609:Beta-Globulins / Q000134:cerebrospinal fluid* / Q000737:chemistry*; D001665:Binding Sites; D002236:Carbohydrate Conformation; D050260:Carbohydrate Metabolism; D002240:Carbohydrate Sequence; D002241:Carbohydrates / Q000737:chemistry*; D002851:Chromatography, High Pressure Liquid; D005643:Fucose / Q000378:metabolism; D005690:Galactose / Q000032:analysis; D006031:Glycosylation; D006801:Humans; D019746:Intramolecular Oxidoreductases; D054834:Lipocalins; D008969:Molecular Sequence Data; D019158:N-Acetylneuraminic Acid; D009439:Neuraminidase / Q000378:metabolism; D009844:Oligosaccharides / Q000737:chemistry; D043524:Peptide-N4-(N-acetyl-beta-glucosaminyl) Asparagine Amidase; D012091:Repetitive Sequences, Nucleic Acid; D012794:Sialic Acids / Q000032:analysis / Q000737:chemistry; D014357:Trypsin / Q000378:metabolism
D001609:Beta-Globulins; D002241:Carbohydrates; D054834:Lipocalins; D009844:Oligosaccharides; D012794:Sialic Acids; D005643:Fucose; D009439:Neuraminidase; D014357:Trypsin; D000581:Amidohydrolases; D043524:Peptide-N4-(N-acetyl-beta-glucosaminyl) Asparagine Amidase; D019746:Intramolecular Oxidoreductases; C022466:prostaglandin R2 D-isomerase; D019158:N-Acetylneuraminic Acid; D000117:Acetylglucosamine; D005690:Galactose