Structure determination of oligosaccharides isolated from Cad erythrocyte membranes by permethylation analysis and 500‐MHz 1H‐NMR spectroscopy

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Abstract
Alkaline borohydride reductive cleavage (β‐elimination) of glycophorin A isolated from one individual of the rare blood group Cad, resulted in the release of six acidic oligosaccharide‐alditols which were separated by high‐performance liquid chromatography (HPLC) on an alkyl amine silicagel column. The structure of four of them has been determined by the application of methanolysis analysis and 1H‐NMR spectroscopy at 500 MHz. The structures and relative amounts were as follows: oligosaccharide 1: NeuAc(α2–3)Gal(β1 – 3)GalNAcol (3.5%); oligosaccharide 3: GalNAc(β1–4)[NeuAc(α2–3)]Gal(β1–3)GalNAc‐ol (10.5%); oligosaccharide 5: NeuAc(α2–3)Gal(β1–3)[NeuAc(α2–6)]GalNAc‐ol (10.4%); oligosaccharide 6: GalNAc(β1–4)[NeuAc(α2–3)]Gal(β1–3)[NeuAc(α2–6)]GalNAc‐ol (71.2%). The two other oligosaccharides (2 and 4) were obtained in very low amount. The major pentasaccharide (oligosaccharide 6) carries the blood group Cad determinant and is a potent inhibitor of human anti‐Sda antibody.