Tai G H, Nieduszynski I A, Fullwood N J, Huckerby T N
Department of Biological Sciences, Institute of Environmental and Natural Sciences, Lancaster University, Bailrigg, Lancaster LA1 4YQ, United Kingdom.
J Biol Chem. 1997 Nov 7;272(45):28227-31. doi: 10.1074/jbc.272.45.28227.
The keratan sulfate-containing proteoglycans were isolated from fourteen pooled human corneas (thirteen from 61- to 86-year-olds, plus one from a 12-year-old). These proteoglycans were subjected to digestion with the enzyme keratanase II, and the released oligosaccharides, which included nonreducing termini and repeat region oligosaccharides but not linkage regions, were reduced with alkaline borohydride and identified on two separate ion-exchange columns. Both of the latter had been calibrated with samples, most of which had been derived from bovine corneal keratan sulfate (Tai, G.-H., Huckerby, T. N., and Nieduszynski, I. A. (1996) J. Biol. Chem. 271, 23535-23546) and all of which had been fully characterized by NMR spectroscopic analysis. The capping structures identified in human corneal keratan sulfates occurred in the relative proportions: NeuAcalpha(2-6)- >NeuAcalpha(2-3)- >GalNAc(S)beta(1-3)-. The other groups of capping structures which had been identified in bovine corneal keratan sulfate, i.e. NeuGcalpha(2-3)-, NeuGcalpha(2-6)-, GlcNAc(S)beta(1-3)- were absent, although the possibility of the presence of some Galalpha(1-3)- structures could not be excluded. In addition, the human sample showed significantly higher levels of alpha(1-3)-fucosylated repeat region structures than did the bovine sample, and it is not clear whether this reflects a species or age dependence as the bovine corneas were from young animals, whereas the human corneas were predominantly from an older group. The charge densities and keratan sulfate chain sizes of the human and bovine keratan sulfate-containing proteoglycans were seen to be similar.
从14个合并的人眼角膜中分离出含硫酸角质素的蛋白聚糖（其中13个来自61至86岁的人，另一个来自12岁的人）。这些蛋白聚糖用角质酶II进行消化，释放出的寡糖（包括非还原末端和重复区域寡糖，但不包括连接区域）用碱性硼氢化钠还原，并在两个单独的离子交换柱上进行鉴定。后两者均用样品进行了校准，其中大多数样品来自牛眼角膜硫酸角质素（Tai, G.-H., Huckerby, T. N., and Nieduszynski, I. A. (1996) J. Biol. Chem. 271, 23535 - 23546），并且所有样品均已通过核磁共振光谱分析进行了全面表征。在人眼角膜硫酸角质素中鉴定出的封端结构的相对比例为：NeuAα(2 - 6)- > NeuAα(2 - 3)- > GalNAc(S)β(1 - 3)-。在牛眼角膜硫酸角质素中鉴定出的其他封端结构组，即NeuGα(2 - 3)-、NeuGα(2 - 6)-、GlcNAc(S)β(1 - 3)-不存在，尽管不能排除存在一些Galα(1 - 3)-结构的可能性。此外，人样品中α(1 - 3)-岩藻糖基化重复区域结构的水平明显高于牛样品，并且尚不清楚这是反映物种还是年龄依赖性，因为牛角膜来自幼龄动物，而人角膜主要来自老年组。观察到人和牛含硫酸角质素的蛋白聚糖的电荷密度和硫酸角质素链大小相似。
