Endo-beta-1,4-xylanase families: differences in catalytic properties
Endo-beta-1,4-xylanase families: differences in catalytic properties
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DOI：
10.1016/s0168-1656(97)00096-5
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发表时间：
1997-09-16
影响因子：
4.1
通讯作者：
Kluepfel, D
中科院分区：
文献类型：
--
作者：
Biely, P;Vrsanska, M;Kluepfel, D
属于聚糖酶家族10（以前为F）和11（以前为G）的微生物内切β-1，4-木聚糖酶（EX，EC 3.2.1.8）在它们对4-O-甲基-D-葡糖醛酸-D-木聚糖和rhodymenan（一种β-1，3-β-1，4-木聚糖）的作用上不同。两种高分子量EX（家族10），变铅青链霉菌的白色隐球菌EX和XlnA，从葡糖醛酸木聚糖醛四糖醛酸中释放出最短的酸性片段，并从罗地曼中释放出结构Xyl β 1-3Xyl β 1-4Xyl的异构木三糖，作为含有β-1，3-键的最短片段。低分子量EX（家族11），例如里氏木霉酶和S.从葡糖醛酸木聚糖中释放出醛五糖醛酸作为最短片段，从罗地美聚糖中释放出异构的木四糖作为含有β-1，3-键的最短片段。通过以下方法确定寡糖的结构：NMR光谱、全-O-甲基化化合物的质谱和β-木糖苷酶和EX的酶水解，然后通过色谱法分析产物。片段的结构在多糖中限定了被酶攻击和未被酶攻击的键。与家族11的EX相比，家族10的EX在主链中需要更少数量的未取代的连续β-1，4-吡喃木糖基单元，并且在罗地美聚糖中需要更少数量的连续β-1，4-吡喃木糖基键。这些结果以及家族10的EX更大的催化多功能性表明家族10的EX具有比家族11的EX更小的底物结合位点。这一建议与家族10的EX比家族11的EX对较短的线性β-1，4-木寡糖显示出更高的亲和力的发现一致。最后结合相关文献数据对结果进行了讨论，以更好地理解这组聚糖酶的结构-功能关系。(C)1997年Elsevier Science B.V.
Microbial endo-beta-1,4-xylanases (EXs, EC 3.2.1.8) belonging to glycanase families 10 (formerly F) and 11 (formerly G) differ in their action on 4-O-methyl-D-glucurono-D-xylan and rhodymenan, a beta-1,3-beta-1,4-xylan. Two high molecular mass EXs (family 10), the Cryptococcus albidus EX and XlnA of Streptomyces lividans, liberate from glucuronoxylan aldotetrauronic acid as the shortest acidic fragment, and from rhodymenan an isomeric xylotriose of the structure Xyl beta 1-3Xyl beta 1-4Xyl as the shortest fragment containing a beta-1,3-linkage. Low molecular mass EXs (family 11), such as the Trichoderma reesei enzymes and XlnB and XlnC of S. lividans, liberate from glucuronoxylan an aldopentauronic acid as the shortest fragment, and from rhodymenan an isomeric xylotetraose as the shortest fragment containing a beta-1,3-linkage. The structure of the oligosaccharides was established by: NMR spectroscopy, mass spectrometry of per-O-methylated compounds and enzymic hydrolysis by beta-xylosidase and EX, followed by analysis of products by chromatography. The structures of the fragments define in the polysaccharides the linkages attacked and non-attacked by the enzymes. EXs of family 10 require a lower number of unsubstituted consecutive beta-1,4-xylopyranosyl units in the main chain and a lower number of consecutive beta-1,4-xylopyranosyl linkages in rhodymenan than EXs of family 11. These results, together with a greater catalytic versatility of EXs of family 10, suggest that EXs of family 10 have substrate binding sites smaller than those of EXs of family 11. This suggestion is in agreement with the finding that EXs of family 10 show higher affinity for shorter linear beta-1,4-xylooligosaccharides than EXs of family 11. The results are discussed with relevant literature data to understand better the structure-function relationship in this group of glycanases. (C) 1997 Elsevier Science B.V.