The β-1,4-endogalactanase A gene from Aspergillus niger is specifically induced on arabinose and galacturonic acid and plays an important role in the degradation of pectic hairy regions
The β-1,4-endogalactanase A gene from Aspergillus niger is specifically induced on arabinose and galacturonic acid and plays an important role in the degradation of pectic hairy regions
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DOI：
10.1046/j.1432-1033.2002.03199.x
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发表时间：
2002-10-01
期刊：
影响因子：
--
通讯作者：
Visser, J
中科院分区：
文献类型：
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作者：
de Vries, RP;Parenicová, L;Visser, J
尼日尔β-1，4-内切半乳聚糖酶编码基因（galA）的克隆和表征。galA在A.尼日尔仅在存在甜菜果胶、d-半乳糖醛酸和l-阿拉伯糖的情况下检测到，这表明galA与果胶分解基因以及阿拉伯聚糖分解基因都是共调节的。相应的酶，内切半乳聚糖酶A（GALA），含有先前鉴定的荧光假单胞菌β-1，4-内切半乳聚糖酶的两个活性位点残基。该酶的分子量为48.5 kDa，最适pH为4至4.5。马铃薯、洋葱和大豆的阿拉伯半乳聚糖与GALA的孵育最初导致d-半乳糖三糖和d-半乳糖四糖的释放，而长时间孵育主要导致d-半乳糖和d-半乳糖二糖。MALDI-TOF分析揭示了L-阿拉伯糖取代的D-半乳寡糖从大豆阿拉伯半乳聚糖中的释放。这是首次报道β-1，4-内切半乳聚糖酶释放取代的d-半乳寡糖的能力。GALA对在还原端被D-葡萄糖取代的D-低聚半乳糖没有活性。
The Aspergillus niger beta-1,4-endogalactanase encoding gene (galA ) was cloned and characterized. The expression of galA in A. niger was only detected in the presence of sugar beet pectin, d-galacturonic acid and l-arabinose, suggesting that galA is coregulated with both the pectinolytic genes as well as the arabinanolytic genes. The corresponding enzyme, endogalactanase A (GALA), contains both active site residues identified previously for the Pseudomonas fluorescens beta-1,4-endogalactanase.The galA gene was overexpressed to facilitate purification of GALA. The enzyme has a molecular mass of 48.5 kDa and a pH optimum between 4 and 4.5. Incubations of arabinogalactans of potato, onion and soy with GALA resulted initially in the release of d-galactotriose and d-galactotetraose, whereas prolonged incubation resulted in d-galactose and d-galactobiose, predominantly. MALDI-TOF analysis revealed the release of l-arabinose substituted d-galacto-oligosaccharides from soy arabinogalactan. This is the first report of the ability of a beta-1,4-endogalactanase to release substituted d-galacto-oligosaccharides. GALA was not active towards d-galacto-oligosaccharides that were substituted with d-glucose at the reducing end.