Nimtz Manfred, Conradt Harald S, Mann Karlheinz
Gesellschaft für Biotechnologische Forschung, Abteilung Strukturbiologie, Protein Glycosylation Group, D-38124 Braunschweig, Germany.
Biochim Biophys Acta. 2004 Nov 18;1675(1-3):71-80. doi: 10.1016/j.bbagen.2004.08.007.
The avian eggshell matrix protein ovocleidin-116 (OC-116) contains two N-glycosylation sites in its sequence. One of them, 293N-D-S, is modified only marginally while the second one, 62N-Q-T, is completely occupied by N-linked glycans. The glycopeptide bearing the modified site was isolated by size exclusion chromatography and reversed phase HPLC after cleavage of the protein with lysyl endopeptidase. The carbohydrate structures attached to Asn62 were determined by carbohydrate compositional analysis, methylation analysis and electrospray MS/MS. We identified 17 different oligosaccharide structures. Four of them were of the high-mannose type, eight were hybrid type and five were complex type structures. Both, hybrid and complex type glycans comprised core-fucosylated and peripherally fucosylated structures. Most of the antennae contained the relatively rare lacdiNAc (GalNAcbeta1-4GlcNAc) motif, which was fucosylated in 9 out of 15 structures. The lacNAc (Galbeta1-4GlcNAc) motif, which is the more frequent motif in mammals, only occurred in 3 of the 17 glycoforms. This is the first detailed study of N-glycan structures occurring in an avian shell-specific protein and, to our knowledge, the first description of fucosylated lacdiNAc structures present in avian glycoproteins.
禽蛋壳基质蛋白卵壳素-116（OC-116）在其序列中含有两个N-糖基化位点。其中一个位点293N-D-S仅有少量修饰，而另一个位点62N-Q-T则完全被N-连接聚糖占据。在用赖氨酰内肽酶裂解蛋白质后，通过尺寸排阻色谱和反相高效液相色谱分离出带有修饰位点的糖肽。通过碳水化合物组成分析、甲基化分析和电喷雾串联质谱确定连接到Asn62的碳水化合物结构。我们鉴定出17种不同的寡糖结构。其中4种为高甘露糖型，8种为杂合型，5种为复合型结构。杂合型和复合型聚糖均包含核心岩藻糖基化和外周岩藻糖基化结构。大多数天线含有相对罕见的乳糖胺（GalNAcbeta1-4GlcNAc）基序，在15种结构中有9种被岩藻糖基化。乳糖胺（Galbeta1-4GlcNAc）基序在哺乳动物中更为常见，仅在17种糖型中的3种中出现。这是对禽蛋壳特异性蛋白中N-聚糖结构的首次详细研究，据我们所知，也是对禽糖蛋白中岩藻糖基化乳糖胺结构的首次描述。
