Sequential degradation of a chondroitin sulphate trisaccharide by lysosomal enzymes from embryonic-chick epiphysial cartilage.
Sequential degradation of a chondroitin sulphate trisaccharide by lysosomal enzymes from embryonic-chick epiphysial cartilage.
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来自胚胎鸡骨骺软骨的溶酶体酶对硫酸软骨素三糖的连续降解。
DOI：
10.1042/bj1790007
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发表时间：
1979
期刊：
影响因子：
--
通讯作者：
Å. Wasteson
中科院分区：
文献类型：
--
作者：
B. Ingmar;Å. Wasteson
由含\(^{35}S\)或\(^{14}C\)标记的硫酸软骨素制备的二硫酸化三糖\(D - N -\)乙酰半乳糖胺硫酸酯 - \(\beta - D -\)葡萄糖醛酸 - \(\beta - D - N -\)乙酰半乳糖胺硫酸酯，与来自鸡胚骺软骨的溶酶体酶制剂一起孵育。通过对反应产物的分析证明了降解的发生。通过使用适当的中间产物作为底物，并结合特异性酶抑制剂，结果表明降解从非还原端依次进行。首先由硫酸酯酶（优先水解6位的硫酸酯基团）启动，接着是\(\beta - N -\)乙酰半乳糖胺酶和\(\beta -\)葡萄糖醛酸酶，将底物转化为单糖和无机硫酸盐。后一种酶优先作用于在己糖胺残基的\(C - 4\)位带有硫酸酯基团的二糖。硫酸软骨素寡糖的产生可能是由一种内切糖苷酶的作用引起的，此前已在鸡胚软骨中得到证实。因此，内切酶和外切酶可能在硫酸软骨素的溶酶体降解中形成一个功能单元。
The disulphated trisaccharide D-N-acetylgalactosamine sulphate-beta-D-glucuronic acid-beta-D-N-acetylgalactosamine sulphate prepared from 35S- or 14C-labelled chondroitin sulphate was incubated with a preparation of lysosomal enzymes from embryonic-chick epiphysial cartilage. Degradation was demonstrated by analysis of the reaction products. By use of the appropriate intermediate products as substrates, in conjunction with specific enzyme inhibitors, it was shown that the degradation proceeded sequentially from the non-reducing end. It was initiated by sulphatase (preferentially hydrolysing sulphate ester groups at the 6-position), followed by beta-N-acetylgalactosaminidase and beta-glucuronidase, converting the substrate into monosaccharides and inorganic sulphate. The latter enzyme preferentially attacked disaccharides carrying their sulphate ester group at C-4 of the hexosamine residue. Generation of chondroitin sulphate oligosaccharides may occur by the action of an endoglycosidase, previously demonstrated in embryonic-chick cartilage. Endo- and exo-enzymes may thus form a functional unit in lysosomal degradation of chondroitin sulphate.