牛脑核糖核酸酶天冬酰胺连接糖链的结构

The structure of the asparagine-linked sugar chains of bovine brain ribonuclease.

作者信息

Katoh H, Ohgi K, Irie M, Endo T, Kobata A

机构信息

Department of Microbiology, Hoshi College of Pharmacy, Tokyo, Japan.

出版信息

Carbohydr Res. 1990 Jan 15;195(2):273-93. doi: 10.1016/0008-6215(90)84171-p.

DOI:10.1016/0008-6215(90)84171-p

PMID:2331705

Abstract

The asparagine-linked sugar chains of bovine brain ribonuclease were quantitatively released as oligosaccharides from the polypeptide backbone by hydrazinolysis. After N-acetylation, they were converted into radioactively-labeled oligosaccharides by NaB3H4 reduction. The radioactive oligosaccharide mixture was fractionated by ion-exchange chromatography, and the acidic oligosaccharides were converted into neutral oligosaccharides by sialidase digestion. The neutral oligosaccharides were then fractionated by Bio-Gel P-4 column chromatography. Structural studies of each oligosaccharide by sequential exoglycosidase digestion in combination with methylation analysis revealed that bovine brain ribonuclease showed extensive heterogeneity. It contains bi- and tri-antennary, complex-type oligosaccharides having alpha-D-Manp-(1----3)-[alpha-D-Manp-(1----6)]-beta-D-Manp -(1----4)-beta-D- GlcpNAc-(1----4)-[alpha-L-Fucp-(1----6)]-D-GlcNAc as their common core. Four different outside oligosaccharide chains, i.e., beta-D-Galp-(1----4)-beta-D-GlcpNAc-(1----, alpha-Neu5Ac-(2----6)-beta-D- Galp-(1----4)-beta-D-GlcpNAc-(1----, alpha-Neu5Ac-(2----3)-beta-D-Galp-(1----4)- beta-D-GlcpNAc-(1----, and alpha-D-Galp-(1----3)-beta-D-Galp-(1----4)-beta-D-GlcpNAc-(1----, were found. The preferential distribution of the alpha-D-Galp-(1----3)-beta-D-Galp-(1----4)-beta-D-GlcpNAc group on the alpha-D-Manp-(1----6) arm is a characteristic feature of the sugar chains of this enzyme.

摘要

通过肼解作用，牛脑核糖核酸酶的天冬酰胺连接糖链以寡糖形式从多肽主链上被定量释放出来。N-乙酰化后，通过硼氢化钠还原将它们转化为放射性标记的寡糖。放射性寡糖混合物通过离子交换色谱进行分离，酸性寡糖通过唾液酸酶消化转化为中性寡糖。然后中性寡糖通过Bio-Gel P-4柱色谱进行分离。通过外切糖苷酶顺序消化结合甲基化分析对每个寡糖进行结构研究表明，牛脑核糖核酸酶表现出广泛的异质性。它含有双天线和三天线的复合型寡糖，其共同核心为α-D-甘露糖基-(1→3)-[α-D-甘露糖基-(1→6)]-β-D-甘露糖基-(1→4)-β-D-葡糖胺基-(1→4)-[α-L-岩藻糖基-(1→6)]-D-葡糖胺。发现了四种不同的外部寡糖链，即β-D-半乳糖基-(1→4)-β-D-葡糖胺基-(1→、α-神经氨酸-(2→6)-β-D-半乳糖基-(1→4)-β-D-葡糖胺基-(1→、α-神经氨酸-(2→3)-β-D-半乳糖基-(1→4)-β-D-葡糖胺基-(1→和α-D-半乳糖基-(1→3)-β-D-半乳糖基-(1→4)-β-D-葡糖胺基-(1→。α-D-半乳糖基-(1→3)-β-D-半乳糖基-(1→4)-β-D-葡糖胺基团在α-D-甘露糖基-(1→6)臂上的优先分布是该酶糖链的一个特征。