Complex-type carbohydrates of apolipoprotein-B of human plasma low-density lipoproteins

Two fractions of glycopeptides containingN-glycosidic asparagine-linked glycans were isolated by concanavalin-A-Sepharose affinity chromatography from Pronase digests of apolipoprotein-B of human low-density lipoproteins. Methylation analysis indicated that the non-binding fraction contains about 0.5 mol complex-type tri- or tetra-antennary oligosaccharides per mol lipoprotein. Structures containing a bisectingN-acetylglucosamine were also detected in this fraction. The weakly binding fraction from the chromatography contains the majority of the complex oligosaccharides of apolipoprotein-B, i.e. 5–6 mol of bi-antennary chains of the transferrin-type per mol of lipoprotein. In addition to sialylated structures, branches containing a terminalN-acetylglucosamine residue were detected on the complex-type glycans of apolipoprotein-B.