Tarentino A L, Plummer T H, Maley F
Biochemistry. 1975 Dec 16;14(25):5516-23. doi: 10.1021/bi00696a021.
Methods are presented for separating the three IgM heavy chain sialoglycopeptides associated with asparagines 170, 332, and 395. The core glycopeptide units containing the disaccharide fucosyl-N-acetylglucosamine were obtained through the use of an endo-beta-N-acetylglucosamindase from Diplococcus pneumoniae, following exoglycosidase treatment of the sialoglycopeptides. In addition to the core glycopeptides, high yields of a tetrasaccharide, (Man)3GlcNAc, were obtained. The fucose in the core disaccharide is glycosidically linked to the 6-O position of the N-acetylglucosamine residue in Asn-GlcNAc. This core unit is resistant to glycosyl asparaginase, but becomes susceptible to hydrolysis on removal of the fucosyl residue by a purified hen oviduct alpha-L-fucosidase. The core sequence of the immunoglobulin M sialoglycopeptides appears to be similar to that of most other asparagine-linked oligosaccharides in consisting of a basic unit composed of beta-D-Man-(1 leads to 4)beta-D-GlcNAc(1 leads to 4)beta-D-GlcNAc(1 leads to 4), but with L fucose linked alpha-(1 leads to 6) to the proximal GlcNAc. The two nonreducing terminal ends of (Man)3GlcNAc are linked to beta-D-Man by alpha-(1 leads to 3) and alpha(1 leads to 6) bonds, respectively.
介绍了分离与天冬酰胺170、332和395相关的三种免疫球蛋白M重链唾液酸糖肽的方法。在对唾液酸糖肽进行外切糖苷酶处理后，通过使用来自肺炎双球菌的内切β-N-乙酰氨基葡糖苷酶获得了含有二糖岩藻糖基-N-乙酰葡糖胺的核心糖肽单元。除了核心糖肽外，还获得了高产率的四糖（Man）3GlcNAc。核心二糖中的岩藻糖通过糖苷键连接到Asn-GlcNAc中N-乙酰葡糖胺残基的6-O位。该核心单元对糖基天冬酰胺酶具有抗性，但在用纯化的鸡输卵管α-L-岩藻糖苷酶去除岩藻糖基残基后变得易于水解。免疫球蛋白M唾液酸糖肽的核心序列似乎与大多数其他天冬酰胺连接的寡糖相似，由一个基本单元组成，该基本单元由β-D-Man-（1→4）β-D-GlcNAc（1→4）β-D-GlcNAc（1→4）组成，但L-岩藻糖通过α-（1→6）连接到近端GlcNAc。（Man）3GlcNAc的两个非还原末端分别通过α-（1→3）和α-（1→6）键与β-D-Man相连。
