Gumerov Vadim M, Rakitin Andrey L, Mardanov Andrey V, Ravin Nikolai V
Centre "Bioengineering", Russian Academy of Sciences, Moscow 117312, Russia.
Archaea. 2015 Oct 11;2015:978632. doi: 10.1155/2015/978632. eCollection 2015.
We expressed a putative β-galactosidase Asac_1390 from hyperthermophilic crenarchaeon Acidilobus saccharovorans in Escherichia coli and purified the recombinant enzyme. Asac_1390 is composed of 490 amino acid residues and showed high sequence similarity to family 1 glycoside hydrolases from various thermophilic Crenarchaeota. The maximum activity was observed at pH 6.0 and 93°C. The half-life of the enzyme at 90°C was about 7 hours. Asac_1390 displayed high tolerance to glucose and exhibits hydrolytic activity towards cellobiose and various aryl glucosides. The hydrolytic activity with p-nitrophenyl (pNP) substrates followed the order pNP-β-D-galactopyranoside (328 U mg(-1)), pNP-β-D-glucopyranoside (246 U mg(-1)), pNP-β-D-xylopyranoside (72 U mg(-1)), and pNP-β-D-mannopyranoside (28 U mg(-1)). Thus the enzyme was actually a multifunctional β-glycosidase. Therefore, the utilization of Asac_1390 may contribute to facilitating the efficient degradation of lignocellulosic biomass and help enhance bioconversion processes.
我们在大肠杆菌中表达了嗜热泉古菌嗜酸糖硫叶菌的一种假定的β-半乳糖苷酶Asac_1390，并对重组酶进行了纯化。Asac_1390由490个氨基酸残基组成，与各种嗜热泉古菌的1型糖苷水解酶具有高度的序列相似性。在pH 6.0和93°C时观察到最大活性。该酶在90°C下的半衰期约为7小时。Asac_1390对葡萄糖具有高度耐受性，对纤维二糖和各种芳基葡萄糖苷具有水解活性。对硝基苯基（pNP）底物的水解活性顺序为：pNP-β-D-吡喃半乳糖苷（328 U mg-1）、pNP-β-D-吡喃葡萄糖苷（246 U mg-1）、pNP-β-D-吡喃木糖苷（72 U mg-1）和pNP-β-D-吡喃甘露糖苷（28 U mg-1）。因此，该酶实际上是一种多功能β-糖苷酶。因此，Asac_1390的利用可能有助于促进木质纤维素生物质的有效降解，并有助于增强生物转化过程。
