Center for Pan-third Pole Environment, Lanzhou University, Lanzhou 730000, China; College of Ecology, Lanzhou University, Lanzhou 730000, China; CAS Key Laboratory for Biological Effects of Nanomaterials and Nanosafety, National Center for Nanoscience and Technology, Chinese Academy of Sciences, Beijing 100190, China.
Center for Pan-third Pole Environment, Lanzhou University, Lanzhou 730000, China.
Int J Biol Macromol. 2024 Oct;277(Pt 3):134202. doi: 10.1016/j.ijbiomac.2024.134202. Epub 2024 Jul 30.
Cellobiose 2-epimerase (CE) catalyzes the conversion of the lactose into its high-value derivatives, epilactose and lactulose, which has great prospects in food applications. In this study, CE sequences from the Qinghai-Tibet Plateau gene catalogue, we screened these for structural flexibility through molecular dynamics simulation to identify potential psychrophilic CE candidates. One such psychrophilic CE we termed psyCE demonstrated exceptional epimerization activity, achieving an optimum activity of 122.2 ± 1.6 U/mg. Its kinetic parameters (K and K) for epimerization activity were 219.9 ± 5.6 s and 261.9 ± 18.1 mM, respectively, representing the highest K recorded among known cold-active CEs. Notably, this is the first report of a psychrophilic CE. The psyCE can effectively produce epilactose at 8 °C, converting 20.3 % of 200 mM lactose into epilactose within four hours. These findings suggest that psyCE is highly suitable for cryogenic food processing, and glaciers may serve as a valuable repository of psychrophilic enzymes.
纤维二糖 2-差向异构酶（CE）可催化乳糖转化为具有高附加值的衍生物——表乳糖和乳果糖，在食品应用方面具有广阔的前景。在本研究中，我们从青藏高原基因目录中筛选 CE 序列，通过分子动力学模拟筛选这些序列的结构灵活性，以鉴定潜在的嗜冷 CE 候选物。我们将其中一种嗜冷 CE 命名为 psyCE，它表现出出色的差向异构酶活性，最适活性达到 122.2±1.6 U/mg。其差向异构酶活性的动力学参数（K 和 K）分别为 219.9±5.6 s 和 261.9±18.1 mM，这是已知冷活性 CEs 中记录到的最高 K 值。值得注意的是，这是首次报道嗜冷 CE。psyCE 可以在 8°C 下有效生产表乳糖，在 4 小时内将 200mM 乳糖中的 20.3%转化为表乳糖。这些发现表明 psyCE 非常适合低温食品加工，而冰川可能是嗜冷酶的宝贵资源库。
