Intracellular β-galactosidase (E.C 3.2.1.23) produced by the thermoacidophilic archeon Picrophilus torridus DSM 9790 was purified to homogeneity using a combination of DEAE Sepharose, gel filtration, hydroxyapatite and chromatofocusing chromatographies. LC–MS/MS analysis was used to confirm the identity of the purified protein. The enzyme was found to be a homotrimer, with a molecular mass of 157.0 kDa and an isoelectric point of 5.7. To our knowledge, this enzyme has the lowest pH optimum of any intracellular β-galactosidase characterized to date. Maximal activity was exhibited at acidic pH values of 5.0–5.5 and at 70 °C. The enzyme retained > 95% activity after heating to 70 °C for 1 h, or after incubation at pH 5.5 for 1 h. The enzyme may be of interest for high-temperature bioprocessing, such as in the production of lactulose. This investigation suggests that the β-galactosidase activity produced by P. torridus is potentially more useful than several enzymes already characterized for such an application.

中文翻译：

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一种新的嗜热β-半乳糖苷嗜热β-半乳糖苷酶的纯化和表征，具有潜在的工业应用价值。

嗜热嗜酸菌Picrophilus torridus产生的细胞内β-半乳糖苷酶（EC 3.2.1.23）使用DEAE Sepharose，凝胶过滤，羟基磷灰石和色谱聚焦色谱法的组合将DSM 9790纯化至均质。LC-MS / MS分析用于确认纯化蛋白的身份。发现该酶是同三聚体，分子量为157.0kDa，等电点为5.7。据我们所知，该酶具有迄今为止表征的任何细胞内β-半乳糖苷酶的最低pH最佳值。在酸性pH值为5.0–5.5且在70°C时显示出最大的活性。加热至70°C 1 h或在pH 5.5下孵育1 h后，酶保留> 95％的活性。该酶可能对高温生物加工（例如在乳果糖的生产中）感兴趣。这项研究表明，P。torridus产生的β-半乳糖苷酶活性 与已经针对这种应用表征的几种酶相比，“大豆”可能更有用。