Biomass Research Platform Team, Biomass Engineering Program, Research Cluster for Innovation, RIKEN, 1-7-29 Suehiro-cho, Tsurumi-ward, Yokohama, Kanagawa, Japan.
Appl Biochem Biotechnol. 2013 Mar;169(6):1910-8. doi: 10.1007/s12010-012-9992-1. Epub 2013 Jan 25.
The termite symbiotic system is one of the efficient lignocellulose degradation systems. We tried to express and characterize a novel cellulolytic enzyme from this system. Here, we report the isolation of an endo-β-1,4-glucanase gene homolog of glycoside hydrolase family 45 from a symbiotic protistan community of Reticulitermes speratus. Heterologous expression of this gene was performed using the expression system of Aspergillus oryzae. Analysis of enzymatic properties revealed 786 μmol/min/mg protein in specific activity, a V max of 833.0 units/mg protein, and a K m value of 2.58 mg/ml with carboxymethyl cellulose as the substrate. Thin-layer chromatography analysis showed that RsSymEG2 produces cellobiose from cellodextrins larger than cellohexaose. This enzyme showed high specific activity like other endo-β-1,4-glucanases from the symbiotic system of termites. It means that the termite symbiotic system is a good resource for highly active endo-β-1,4-glucanases.
白蚁共生系统是一种高效的木质纤维素降解系统。我们试图从这个系统中表达和鉴定一种新型的纤维素酶。在这里，我们报道了从台湾乳白蚁共生原生动物群落中分离到糖苷水解酶家族 45 的内切 β-1,4-葡聚糖酶基因同源物。使用米曲霉表达系统进行了该基因的异源表达。酶学性质分析表明，该酶以羧甲基纤维素为底物时，比活为 786 μmol/min/mg 蛋白，V max 为 833.0 单位/mg 蛋白，K m 值为 2.58 mg/ml。薄层层析分析表明 RsSymEG2 能够从纤维二糖开始水解较大的纤维寡糖。与其他来自白蚁共生系统的内切 β-1,4-葡聚糖酶一样，该酶具有较高的比活力。这意味着白蚁共生系统是高活性内切 β-1,4-葡聚糖酶的良好来源。
