Tanaka A, Iwase H, Hiki Y, Kokubo T, Ishii-Karakasa I, Toma K, Kobayashi Y, Hotta K
Analytical Research Laboratory, Asahi Chemical Industry Co., Ltd., Fuji, Shizuoka, Japan.
Glycoconj J. 1998 Oct;15(10):995-1000. doi: 10.1023/a:1006989910120.
Glycopeptides containing the N-linked oligosaccharide from human serum IgA1 were analyzed by matrix-assisted laser desorption ionization time-of-flight mass spectrometry (MALDI-TOFMS). Two glycopeptides, GP1 and GP2, prepared from the endoproteinase Asp-N digest of the IgA1 heavy chain, were derived from the CH2 domain (N-glycan site at Asn263) and the tailpiece portion (N-glycan site at Asn459), respectively. The structure of the attached sugar chain was deduced from the mass number of the glycopeptide and confirmed by a two-dimensional mapping technique for a pyridylaminated oligosaccharide. GP1 was composed of two major components having a fully galactosylated bianntena sugar chain with or without a bisecting N-acetylglucosamine (GlcNAc) residue. On the other hand, the GP2 fraction corresponded to the glycopeptides having a fully galactosylated and fucosylated bianntena sugar chain partly bearing a bisecting GlcNAc residue. Thus, the site-specific fucosylation of the N-linked oligosaccharide on the tailpiece of the alpha1 chain became evident for normal human serum IgA1.
采用基质辅助激光解吸电离飞行时间质谱（MALDI-TOFMS）分析了含有人血清IgA1 N-连接寡糖的糖肽。从IgA1重链的天冬氨酸内肽酶Asp-N消化产物制备的两种糖肽GP1和GP2，分别来源于CH2结构域（Asn263处的N-聚糖位点）和尾段部分（Asn459处的N-聚糖位点）。根据糖肽的质量数推导连接糖链的结构，并通过对吡啶氨基化寡糖的二维图谱技术进行确认。GP1由两个主要成分组成，具有完全半乳糖基化的双天线糖链，带有或不带有平分型N-乙酰葡糖胺（GlcNAc）残基。另一方面，GP2部分对应于具有完全半乳糖基化和岩藻糖基化的双天线糖链且部分带有平分型GlcNAc残基的糖肽。因此，α1链尾段上N-连接寡糖的位点特异性岩藻糖基化在正常人血清IgA1中变得明显。
