Separation and Some Properties of Two Intracellular β-Glucosidases of Sporotrichum (Chrysosporium) thermophile
Separation and Some Properties of Two Intracellular β-Glucosidases of Sporotrichum (Chrysosporium) thermophile
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DOI：
10.1128/aem.41.4.924-931.1981
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发表时间：
1981-04
影响因子：
4.4
通讯作者：
H. Meyer;G. Canevascini
中科院分区：
文献类型：
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作者：
H. Meyer;G. Canevascini
通过凝胶色谱或等电聚焦将来自纤维素分解真菌嗜热孢子丝菌（Sporotrichum（Chrysosporium）thermophile）（ATCC 42464）的细胞内可诱导的β-葡萄糖苷酶分级分离成组分A和B。酶A（分子量440，000）仅具有芳基-β-葡萄糖苷酶活性，而酶B（分子量40，000）水解几种β-葡萄糖苷，但仅对邻硝基苯基-β-d-吡喃葡萄糖苷（ONPG）具有低活性。两种酶的最适温度均为约50°C。酶A和酶B的最适pH分别为5.6和6.3。酶A的Km（ONPG）值为0.5 mM，酶B的相应值为0.18 mM（ONPG）和0.28 mM（纤维二糖）。当用ONPG测试时，酶B在高于0.4 mM的底物浓度下显示出底物抑制，其可被纤维二糖醇和其它糖醇释放。酶A在pH 4.48时是等电的，酶B在pH 4.64时是等电的。测试了几种抑制剂对酶A和B活性的作用。发现这两种酶在以纤维二糖或纤维素作为碳源的培养物中伴随诱导。
Intracellular, inducible β-glucosidase from the cellulolytic fungus Sporotrichum (Chrysosporium) thermophile (ATCC 42464) was fractionated by gel chromatography or isoelectric focusing into components A and B. Enzyme A (molecular weight 440,000) had only aryl-β-glucosidase activity, whereas enzyme B (molecular weight 40,000) hydrolyzed several β-glucosides but had only low activity against o-nitrophenyl-β-d-glucopyranoside (ONPG). Both enzymes had temperature optima of about 50°C. The pH optimum was 5.6 for enzyme A and 6.3 for enzyme B, respectively. The Km (ONPG) value for enzyme A was 0.5 mM, and the corresponding values for enzyme B were 0.18 mM (ONPG) and 0.28 mM (cellobiose). Enzyme B, when tested with ONPG, showed substrate inhibition at a substrate concentration above 0.4 mM which could be released by cellobiitol and other alditols. Enzyme A was isoelectric at pH 4.48, and enzyme B was isoelectric at pH 4.64. Several inhibitors were tested for their action on the activity of enzymes A and B. Both enzymes were found to be concomitantly induced in cultures with either cellobiose or cellulose as carbon source.