Family 3 β-glucosidase from cellulose-degrading culture of the white-rot fungus Phanerochaete chrysosporium is a glucan 1,3-β-glucosidase
Family 3 β-glucosidase from cellulose-degrading culture of the white-rot fungus Phanerochaete chrysosporium is a glucan 1,3-β-glucosidase
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DOI：
10.1016/s1389-1723(03)80164-0
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发表时间：
2003-06-01
影响因子：
2.8
通讯作者：
Samejima, M
中科院分区：
文献类型：
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作者：
Igarashi, K;Tani, T;Samejima, M
研究了白腐真菌黄孢原毛平革菌纤维素降解菌胞外β-葡萄糖苷酶（BGL）的底物特异性。纯化的BGL的氨基酸测序数据显示，该酶与先前报道的相同真菌的糖苷水解酶（GH）家族3 BGL相同[Li，B.和Renganathan，V.，应用环境微生物学：64，2748-2754（1998）]。BGL可以水解纤维二糖和纤维二糖内酯，但纤维二糖内酯的水解速度比纤维二糖慢得多。此外，纤维二糖内酯抑制纤维二糖水解的BGL，这表明这种酶不能协同纤维二糖脱氢酶（CDH）的纤维素降解P. chrysosporium。除纤维二糖外，BGL还利用各种葡糖基-β-葡糖苷，如槐糖、昆布二糖和龙胆二糖作为底物。在四种底物中，海带二糖（β-1，3-糖苷键）水解最有效。海带寡糖的水解速率与聚合度成正比，BGL对聚合度为25的海带多糖的水解活性与对聚合度为5的海带五糖的水解活性相当。因此，我们得出结论，从P. chrysosporium胞外BGL主要是葡聚糖1，3-β-葡萄糖苷酶（EC 3.2.1.58），这可能在真菌细胞壁代谢中发挥作用，而不是β-葡萄糖苷酶（EC 3.2.1.21），这可能涉及在纤维素降解过程中的β-1，4-葡萄糖苷化合物的水解。
The substrate specificity of an extracellular beta-glucosidase (BGL) from cellulose-degrading culture of the white-rot fungus Phanerochaete chrysosporium was investigated, using a variety of compounds with beta-glucosidic linkages. Amino acid sequencing data for the purified BGL showed that the enzyme is identical to the glycoside hydrolase (GH) family 3 BGL of the same fungus previously reported [Li, B. and Renganathan, V., Appl. Environ. Microbiol., 64, 2748-2754 (1998)]. The BGL can hydrolyze both cellobiose and cellobionolactone, but cellobionolactone was hydrolyzed very much more slowly than cellobiose. Moreover, cellobionolactone inhibited cellobiose hydrolysis by the BGL, suggesting that this enzyme cannot cooperate with cellobiose dehydrogenase (CDH) in cellulose degradation by P. chrysosporium. In addition to cellobiose, BGL utilized various glucosyl-beta-glucosides, such as sophorose, laminaribiose and gentiobiose, as substrates. Among the four substrates, laminaribiose (beta-1,3-glucosidic linkage) was hydrolyzed most effectively. Moreover, the hydrolytic rate of laminarioligosaccharides increased proportionally to the degree of polymerization (DP), and the activity of BGL even towards laminarin with an average DP of 25 was similar to that towards laminaripentaose (DP 5). Therefore, we conclude that the extracellular BGL from P. chrysosporium is primarily a glucan 1,3-beta-glucosidase (EC 3.2.1.58), which might play a role on fungal cell wall metabolism, rather than a beta-glucosidase (EC 3.2.1.21), which might be involved in the hydrolysis of beta-1,4-glucosidic compounds during cellulose degradation.