Kitagawa H, Oyama M, Masayama K, Yamaguchi Y, Sugahara K
Department of Biochemistry, Kobe Pharmaceutical University, Japan.
Glycobiology. 1997 Dec;7(8):1175-80. doi: 10.1093/glycob/7.8.1175.
Decorin is a small fibroblast proteoglycan consisting of a core protein and a single chondroitin/dermatan sulfate chain. The structure of the carbohydrate-protein linkage region of the recombinant decorin expressed in Chinese hamster ovary cells was investigated. The decorin was secreted in the culture medium and isolated by anion-exchange chromatography. The glycosaminoglycan chain was released from the decorin by beta-elimination using alkaline NaBH4, and then digested with chondroitinase ABC. These treatments resulted in a major and a few minor hexasaccharide alditols derived from the carbohydrate-protein linkage region. Their structures were analyzed by enzymatic digestion in conjunction with high-performance liquid chromatography. Two of these compounds have the conventional hexasaccharide core, deltaHexA alpha1-3GalNAc beta1-4GlcA beta1-3Gal beta1-3Gal beta1-4Xyl-ol. One is nonsulfated, and the other is monosulfated on C4 of the GalNAc residue. They represent 12% and 60% of the total linkage region, respectively. The other compound has the hexasaccharide alditol with an internal iduronic acid residue deltaHexA alpha1-3GalNAc(4-sulfate)beta1-4IdoA alpha1-3Gal beta1-3Gal beta1-4Xyl-ol, which was previously demonstrated in one of the five linkage hexasaccharide alditols isolated from dermatan sulfate proteoglycans of bovine aorta (Sugahara et al., J. Biol. Chem., 270, 7204-7212, 1995). The compound accounts for 11% of the total linkage region. These structural variations in the linkage hexasaccharide region of the decorin strikingly contrast to the uniformity demonstrated in the linkage hexasaccharide structure of human inter-alpha-trypsin inhibitor (Yamada et al., Glycobiology, 5, 335-341, 1995) and urinary trypsin inhibitor (Yamada et al., Eur. J. Biochem., 233, 687-693, 1995), both of which have a single chondroitin sulfate chain with a uniform linkage hexasaccharide structure, deltaHexA alpha1-3GalNAc(4-sulfate)beta1-4GlcA beta1-3Gal(4-sulfate)beta1-3Gal beta1-4Xyl, containing a 4-O-sulfated Gal residue.
核心蛋白聚糖是一种由核心蛋白和一条单一的硫酸软骨素/硫酸皮肤素链组成的小成纤维细胞蛋白聚糖。对在中国仓鼠卵巢细胞中表达的重组核心蛋白聚糖的碳水化合物 - 蛋白质连接区结构进行了研究。核心蛋白聚糖分泌于培养基中，并通过阴离子交换色谱法进行分离。使用碱性硼氢化钠通过β消除法从核心蛋白聚糖中释放出糖胺聚糖链，然后用软骨素酶ABC进行消化。这些处理产生了一种主要的和几种次要的源自碳水化合物 - 蛋白质连接区的己糖糖醇。通过酶消化结合高效液相色谱法分析它们的结构。其中两种化合物具有常规的己糖核心结构，即ΔHexAα1-3GalNAcβ1-4GlcAβ1-3Galβ1-3Galβ1-4Xyl-ol。一种是非硫酸化的，另一种在GalNAc残基的C4位上是单硫酸化的。它们分别占连接区总量的12%和60%。另一种化合物具有带有内部艾杜糖醛酸残基的己糖糖醇，即ΔHexAα1-3GalNAc(4-硫酸酯)β1-4IdoAα1-3Galβ1-3Galβ1-4Xyl-ol，这在之前从牛主动脉硫酸皮肤素蛋白聚糖中分离出的五种连接己糖糖醇之一中得到过证明（Sugahara等人，《生物化学杂志》，270，7204 - 7212，1995年）。该化合物占连接区总量的11%。核心蛋白聚糖连接己糖区域的这些结构变异与人类α-胰蛋白酶抑制剂（Yamada等人，《糖生物学》，5，335 - 341，1995年）和尿胰蛋白酶抑制剂（Yamada等人，《欧洲生物化学杂志》，233，687 - 693，1995年）连接己糖结构的一致性形成了显著对比，这两种抑制剂都具有一条单一的硫酸软骨素链且连接己糖结构均匀，即ΔHexAα1-3GalNAc(4-硫酸酯)β1-4GlcAβ1-3Gal(4-硫酸酯)β1-3Galβ1-4Xyl，含有一个4-O-硫酸化Gal残基。
