Kim Hye-Jung, Park Ah-Reum, Lee Jung-Kul, Oh Deok-Kun
Department of Bioscience and Biotechnology, Konkuk University, 1 Hwayang-dong, Gwangjin-gu, Seoul 143-701, Korea.
Biotechnol Lett. 2009 Sep;31(9):1457-62. doi: 10.1007/s10529-009-0018-1. Epub 2009 May 21.
A recombinant putative beta-galactosidase from Thermoplasma acidophilum was purified as a single 57 kDa band of 82 U mg(-1). The molecular mass of the native enzyme was 114 kDa as a dimer. Maximum activity was observed at pH 6.0 and 90 degrees C. The enzyme was unstable below pH 6.0: at pH 6 its half-life at 75 degrees C was 28 days but at pH 4.5 was only 13 h. Catalytic efficiencies decreased as p-nitrophenyl(pNP)-beta-D-fucopyranoside (1067) > pNP-beta-D-glucopyranoside (381) > pNP-beta-D-galactopyranoside (18) > pNP-beta-D-mannopyranoside (11 s(-1) mM(-1)), indicating that the enzyme was a beta-glycosidase.
一种来自嗜酸性嗜热栖热菌的重组假定β-半乳糖苷酶被纯化，呈现为一条单一的57 kDa条带，酶活为82 U mg(-1)。天然酶以二聚体形式存在，分子量为114 kDa。在pH 6.0和90℃时观察到最大活性。该酶在pH 6.0以下不稳定：在pH 6时，其在75℃的半衰期为28天，但在pH 4.5时仅为13小时。催化效率的顺序为对硝基苯基（pNP）-β-D-岩藻糖苷（1067）> pNP-β-D-葡萄糖苷（381）> pNP-β-D-半乳糖苷（18）> pNP-β-D-甘露糖苷（11 s(-1) mM(-1)），表明该酶是一种β-糖苷酶。
