Qualitative analysis of the carbohydrate composition of apolipoprotein H.
The specific binding of digoxigenin-labeled lectins to carbohydrate moieties is used to characterize the carbohydrate chains bound to apolipoprotein H. Our results show that apolipoprotein H is rich in sialic acid linked alpha(2-6) to galactose or N-acetylgalactosamine. Sialic acid is not alpha(2-3)-linked to galactose. Galactose is beta(1-4)-linked to N-acetylglucosamine and beta(1-3)-linked to N-acetylgalactosamine. High-mannose N-glycan chains are barely detectable. After N-glycosidase F treatment the molecular weight is substantially reduced. The main band is 32,500 daltons. Carbohydrate O-linked chains, which are mainly represented by sialic acid, are alpha(2-6)-linked to galactose or N-acetylgalactosamine. Galactose is also organized in O-linked chains and it is beta(1-4)-linked to N-acetylglucosamine and beta(1-3)-linked to acetylgalactosamine. Biochemical analysis of carbohydrate structures reveals that no specific carbohydrate complex is bound to a single isoform.
Gambino
R
R
Dipartimento di Medicina Interna, Universita di Torino, Italy.
Ruiu
G
G
Pagano
G
G
Cassader
M
M
D000116:Acetylgalactosamine / Q000032:analysis; D000581:Amidohydrolases; D001053:Apolipoproteins / Q000737:chemistry; D005690:Galactose / Q000032:analysis; D006023:Glycoproteins / Q000097:blood / Q000737:chemistry* / Q000302:isolation & purification; D006801:Humans; D037102:Lectins; D008970:Molecular Weight; D019158:N-Acetylneuraminic Acid / Q000032:analysis; D009844:Oligosaccharides / Q000737:chemistry* / Q000302:isolation & purification; D043524:Peptide-N4-(N-acetyl-beta-glucosaminyl) Asparagine Amidase; D053482:beta 2-Glycoprotein I
D001053:Apolipoproteins; D006023:Glycoproteins; D037102:Lectins; D009844:Oligosaccharides; D053482:beta 2-Glycoprotein I; D000581:Amidohydrolases; D043524:Peptide-N4-(N-acetyl-beta-glucosaminyl) Asparagine Amidase; D019158:N-Acetylneuraminic Acid; D000116:Acetylgalactosamine; D005690:Galactose