REACTION OF UNSATURATED URONIC-ACID RESIDUES WITH MERCURIC-SALTS - CLEAVAGE OF THE HYALURONIC-ACID DISACCHARIDE 2-ACETAMIDO-2-DEOXY-3-O-(BETA-D-GLUCO-4-ENEPYRANOSYLURONIC ACID)-D-GLUCOSE
REACTION OF UNSATURATED URONIC-ACID RESIDUES WITH MERCURIC-SALTS - CLEAVAGE OF THE HYALURONIC-ACID DISACCHARIDE 2-ACETAMIDO-2-DEOXY-3-O-(BETA-D-GLUCO-4-ENEPYRANOSYLURONIC ACID)-D-GLUCOSE
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DOI：
10.1042/bj2450795
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发表时间：
1987-08-01
影响因子：
4.1
通讯作者：
RODEN, L
中科院分区：
文献类型：
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作者：
LUDWIGS, U;ELGAVISH, A;RODEN, L
用细菌或真菌蠕虫酶降解结缔组织多糖以及随后对反应产物进行表征现在是分析这些化合物的标准方法的一部分。然而，基于使用消除酶的制备和分析工作的范围受到了限制，这是由于缺乏特定去除消除酶反应中产生的不饱和糖醛酸残基的方法。在本研究中，我们已经表明，这些残基被汞盐在温和的条件下切割，不太可能影响寡糖或多糖分子中的其他结构。因此，通过用软骨素酶AC或ABC消化从透明质酸产生的二糖在室温下暴露于pH 5的14 mM-乙酸汞后10分钟内裂解成酮酸和游离N-乙酰葡糖胺。二糖与汞盐的反应用于快速测定放射性透明质酸中葡萄糖醛酸和N-乙酰葡糖胺部分之间的放射性分布，所述放射性透明质酸由IMR-90成纤维细胞从3 H-标记的单糖合成。当前体是[3 H]半乳糖时，在葡萄糖醛酸部分中发现超过95%的掺入放射性。相反，在[3 H]葡糖胺存在下生长的细胞合成了一种多糖，其中几乎所有的标记都位于N-乙酰葡糖胺单元中。从这些实验中可以明显看出，不饱和糖醛酸残基与汞盐的反应提供了一种新的工具，在结缔组织多糖的结构和代谢的研究中具有许多应用潜力。
Degradation of connective-tissue polysaccharides with bacterial or fungal elminases and subsequent characterization of the reaction products are now part of standard methodology for the analysis of these compounds. However, the scope of preparative and analytical work based on the use of eliminases has been limited by the lack of procedures for specific removal of the unsaturated uronic acid residues generated in the eliminase reactions. In the present investigation, we have shown that these residues are cleaved by mercuric salts under mild conditions that are not likely to affect other structures in an oligo- or poly-saccharide molecule. Thus the disaccharide generated from hyaluronic acid by digestion with chondroitinase AC or ABC was cleaved into a keto acid and free N-acetylglucosamine within 10 min at room temperature upon exposure to 14 mM-mercuric acetate at pH 5. The reaction of the disaccharide with mercuric salts was used for ready determination of the distribution of radioactivity between the glucuronic acid and N-acetylglucosamine moieties in radioactive hyaluronic acid that had been synthesized by IMR-90 fibroblasts from 3H-labelled monosaccharides. When the precursor was [3H]galactose, over 95% of the incorporated radioactivity was found in the glucuronic acid moiety. In contrast, cells grown in the presence of [3H]glucosamine synthesized a polysaccharide in which almost all of the label was located in the N-acetylglucosamine units. It is apparent from these experiments that the reaction of unsaturated uronic acid residues with mercuric salts provides a new tool with potential for many applications in the study of the structure and metabolism of connective-tissue polysaccharides.