Glucose-tolerant and/or glucose-stimulated β-glucosidase is of great interest for its industrial utilization in enzymatic digestion of lignocellulosic biomass for biofuel production. In this study, a new gene of β-glucosidase MaGlu1A was cloned from an alginate-degrading marine bacterium Microbulbifer sp. ALW1. The gene of MaGlu1A encoded a 472-amino acid protein classified into the glycosyl hydrolase family 1 (GH1). The recombinant β-glucosidase was overexpressed and purified from Escherichia coli with a molecular mass of 65.0 kDa. Structure analysis illustrated the catalytic acid/base residue Glu186 and nucleophilic residue Glu370 in the enzyme. MaGlu1A displayed optimal activity at 40 °C and pH 4.5, respectively. It had substrate preference to the aryl-β-glycosidic bonds with glucose, fucose, and galactose moieties, in addition to cellobiose. MaGlu1A demonstrated strong stimulation to the supplemental glucose. Site-directed mutagenesis suggested an essential role of Asn242 in glucose stimulation. The enzymatic characterization of MaGlu1A provides general information about its catalytic properties facilitating its practical applications.

耐葡萄糖和/或葡萄糖刺激的 β-葡萄糖苷酶因其在木质纤维素生物质的酶消化以生产生物燃料中的工业应用而备受关注。在这项研究中，从藻酸盐降解的海洋细菌Microbulbifer sp. 中克隆了一个新的 β-葡萄糖苷酶 MaGlu1A 基因。ALW1。MaGlu1A的基因编码一个 472 个氨基酸的蛋白质，属于糖基水解酶家族 1 (GH1)。从大肠杆菌中过表达和纯化重组β-葡萄糖苷酶分子量为 65.0 kDa。结构分析说明了酶中的催化酸/碱残基 Glu186 和亲核残基 Glu370。MaGlu1A 分别在 40 °C 和 pH 4.5 下显示出最佳活性。除了纤维二糖外，它对与葡萄糖、岩藻糖和半乳糖部分的芳基-β-糖苷键具有底物偏好。MaGlu1A 表现出对补充葡萄糖的强烈刺激。定点诱变表明 Asn242 在葡萄糖刺激中起重要作用。MaGlu1A 的酶学表征提供了有关其催化特性的一般信息，以促进其实际应用。