Open AccessStructural studies on the O ‐linked carbohydrate chains of human platelet glycocalicin
Author(s) -
KORREL Sophia A. M.,
CLEMETSON Kenneth J.,
HALBEEK Herman,
KAMERLING Johannis P.,
SIXMA Jan J.,
VLIGENTHART Johannes F. G.
Publication year - 1984
Publication title -
european journal of biochemistry
Language(s) - English
Resource type - Journals
eISSN - 1432-1033
pISSN - 0014-2956
DOI - 10.1111/j.1432-1033.1984.tb08140.x
Subject(s) - chemistry , glycoprotein , biochemistry , protease , oligosaccharide , sepharose , glycoprotein ib , wheat germ agglutinin , carbohydrate , glycosidic bond , chromatography , lectin , enzyme , platelet membrane glycoprotein
Glycocalicin (140 kDa), constituting the main part of glycoprotein Ib (160 kDa), was released from the human platelet membrane by the action of a Ca 2+ ‐dependent protease, present in the platelet cytoplasm and liberated during sonication of the platelet suspension. After activation of the protease by Ca 2+ , the sonicated plateled suspension was subjected to differential centrifugation. The supernatant was applied to a column of wheat germ agglutinin linked to Sepharose 4B; glycocalicin was eluted from the column with 2.5% (w/v) N ‐acetylglucosamine. Glycocalicin was found to contain 40% carbohydrate by weight, representing N ‐ as well as O ‐glycosidically linked carbohydrate chains. The O ‐glycosidic chains were split off by alkaline cleavage in the presence of 3 H‐labelled NaBH 4 . The liberated 3 H‐labelled oligosaccharide‐alditols were fractionated on a DEAE‐Sephadex A‐25 column. The structures of the oligosaccharide‐alditols were investigated by 500‐MHz 1 H‐NMR spectroscopy. The major compound was identified as NeuAcα(2→3)Gal β (1→3)[NeuAcα(2→3)Gal β (1→4)GlcNAc β (1→6)]GalNAc‐ol. Two minor compounds were found to be NeuAcα(2→3)Gal β (1→3)[NeuAcα(2→6)]GalNAc‐ol and NeuAcα(2→3)Gal β (1→3)GalNAc‐ol.