National Engineering Laboratory for Industrial Enzymes, Tianjin Institute of Industrial Biotechnology, Chinese Academy of Sciences, Tianjin 300308, China.
University of Chinese Academy of Sciences, Beijing 100049, China.
Mar Drugs. 2018 Mar 9;16(3):86. doi: 10.3390/md16030086.
Alginate oligosaccharides with different bioactivities can be prepared through the specific degradation of alginate by alginate lyases. Therefore, alginate lyases that can be used to degrade alginate under mild conditions have recently attracted public attention. Although various types of alginate lyases have been discovered and characterized, few can be used in industrial production. In this study, AlgA, a novel alginate lyase with high specific activity, was purified from the marine bacterium sp. Alg07. AlgA had a molecular weight of approximately 60 kDa, an optimal temperature of 40 °C, and an optimal pH of 7.5. The activity of AlgA was dependent on sodium chloride and could be considerably enhanced by Mg or Ca. Under optimal conditions, the activity of AlgA reached up to 8306.7 U/mg, which is the highest activity recorded for alginate lyases. Moreover, the enzyme was stable over a broad pH range (5.0-10.0), and its activity negligibly changed after 24 h of incubation at 40 °C. AlgA exhibited high activity and affinity toward poly-β-d-mannuronate (polyM). These characteristics suggested that AlgA is an endolytic polyM-specific alginate lyase (EC 4.2.2.3). The products of alginate and polyM degradation by AlgA were purified and identified through fast protein liquid chromatography and electrospray ionization mass spectrometry, which revealed that AlgA mainly produced disaccharides, trisaccharides, and tetrasaccharide from alginate and disaccharides and trisaccharides from polyM. Therefore, the novel lysate AlgA has potential applications in the production of mannuronic oligosaccharides and poly-α-l-guluronate blocks from alginate.
具有不同生物活性的海藻酸盐寡糖可以通过海藻酸盐裂解酶对海藻酸盐的特异性降解来制备。因此，最近人们关注能够在温和条件下降解海藻酸盐的海藻酸盐裂解酶。尽管已经发现并表征了各种类型的海藻酸盐裂解酶，但很少有能够在工业生产中使用。在这项研究中，从海洋细菌 sp. Alg07 中纯化出了一种具有高比活性的新型海藻酸盐裂解酶 AlgA。AlgA 的分子量约为 60 kDa，最适温度为 40°C，最适 pH 为 7.5。AlgA 的活性依赖于氯化钠，并可以被 Mg 或 Ca 显著增强。在最佳条件下，AlgA 的活性高达 8306.7 U/mg，这是海藻酸盐裂解酶记录的最高活性。此外，该酶在较宽的 pH 范围（5.0-10.0）内稳定，在 40°C 孵育 24 小时后其活性几乎没有变化。AlgA 对聚-β-d-甘露糖酸盐（polyM）表现出高活性和亲和力。这些特性表明 AlgA 是一种内切聚 M 特异性的海藻酸盐裂解酶（EC 4.2.2.3）。AlgA 降解海藻酸盐和 polyM 的产物通过快速蛋白质液相色谱和电喷雾电离质谱进行了纯化和鉴定，结果表明 AlgA 主要从海藻酸盐中产生二糖、三糖和四糖，从 polyM 中产生二糖和三糖。因此，新型裂解酶 AlgA 在从海藻酸盐生产甘露糖醛酸寡糖和聚-α-l-古洛糖醛酸块方面具有潜在的应用价值。
