College of Natural Resources and Environment, South China Agricultural University, Guangzhou 510642, China.
Guangdong Bioengineering Institute (Guangzhou Sugarcane Industry Research Institute)/Guangdong Provincial Key Lab of Sugarcane Improvement & Biorefinery, Guangzhou 510316, China.
Mar Drugs. 2020 Mar 31;18(4):184. doi: 10.3390/md18040184.
Alginate, an important acidic polysaccharide in marine multicellular algae, has attracted attention as a promising biomass resource for the production of medical and agricultural chemicals. Alginate lyase is critical for saccharification and utilization of alginate. Discovering appropriate and efficient enzymes for depolymerizing alginate into fermentable fractions plays a vital role in alginate commercial exploitation. Herein, a unique alginate lyase, AlgSH7, belonging to polysaccharide lyase 7 family is purified and characterized from an alginate-utilizing bacterium sp. SH-1. The purified AlgSH7 shows a specific activity of 12,908.26 U/mg, and its molecular weight is approximately 66.4 kDa. The optimal temperature and pH of AlgSH7 are 40 °C and pH 9.0, respectively. The enzyme exhibits stability at temperatures below 30 °C and within an extensive pH range of 5.0-9.0. Metal ions including Na, K, Al, and Fe considerably enhance the activity of the enzyme. AlgSH7 displays a preference for poly-mannuronic acid (polyM) and a very low activity towards poly-guluronic acid (polyG). TLC and ESI-MS analysis indicated that the enzymatic hydrolysates mainly include disaccharides, trisaccharides, and tetrasaccharides. Noteworthy, the alginate oligosaccharides (AOS) prepared by AlgSH7 have an eliciting activity against chilling stress in Chinese flowering cabbage ( L.). These results suggest that AlgSH7 has a great potential to design an effective process for the production of alginate oligomers for agricultural applications.
褐藻胶是一种存在于海洋多细胞藻类中的重要酸性多糖，作为一种有前途的生物量资源，已引起人们对其用于生产医药和农用化学品的关注。褐藻胶裂解酶对于褐藻酸盐的糖化和利用至关重要。发现合适且高效的酶将褐藻酸盐解聚成可发酵的片段，对于褐藻酸盐的商业开发具有重要意义。在此，从一株利用褐藻酸盐的细菌 sp. SH-1 中纯化和表征了一种独特的褐藻胶裂解酶 AlgSH7，它属于多糖裂解酶 7 家族。纯化的 AlgSH7 具有 12,908.26 U/mg 的比活性，分子量约为 66.4 kDa。AlgSH7 的最适温度和 pH 分别为 40°C 和 pH 9.0。该酶在低于 30°C 的温度和广泛的 pH 5.0-9.0 范围内稳定。包括 Na、K、Al 和 Fe 在内的金属离子可显著提高酶的活性。AlgSH7 对聚甘露糖酸（polyM）表现出偏好性，而对聚古罗糖酸（polyG）的活性非常低。TLC 和 ESI-MS 分析表明，酶解产物主要包括二糖、三糖和四糖。值得注意的是，由 AlgSH7 制备的褐藻酸盐低聚糖（AOS）对白菜（ L.）的冷胁迫具有激发活性。这些结果表明，AlgSH7 具有很大的潜力，可用于设计一种有效的农业用褐藻酸盐寡聚物生产工艺。
