Ulva is globally distributed specie and has a high economic value. Ulvan is one of the main active substances in Ulva, which has a variety of biological properties. Ulvan lyase degrades ulvan through a β-elimination mechanism which cleaves the β-glycosidic bond between Rha3S and GlcA or IdoA. The complex monosaccharide composition of ulvan makes it promising for use in food and pharmaceutical applications. This thesis explores a putative ulvan lyase from Alteromonas sp. KUL_42. We expressed and purified the protein, performed a series of characterizations and signal peptide had been removed. The results showed that the protein molecular weight of ULA-2 was 53.97 kDa, and it had the highest catalytic activity at 45 °C and pH 8.0 in Tris-HCl buffer. The Km and Vmax values were 2.24 mg · mL-1 and 2.048 μmol · min-1 · mL-1, respectively. The activity of ULA-2 was able to maintain more than 80% at 20 ~ 30 °C. ESI-MS analysis showed that the primary end-products were mainly disaccharides to tetrasaccharides. The study of ULA-2 enriches the ulvan lyase library, promotes the development and high-value utilization of Ulva resources, and facilitates further research applications of ulvan lyase in ulva oligosaccharides.

中文翻译：

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新型绿藻硫化多糖裂解酶的生化表征及其在绿藻硫化多利用和石莼寡糖制备中的应用。

石莼是全球分布的物种，具有很高的经济价值。石莼是石莼中的主要活性物质之一，具有多种生物学特性。绿藻多糖裂解酶通过 β-消除机制降解绿藻多糖，该机制裂解 Rha3S 和 GlcA 或 IdoA 之间的 β-糖苷键。绿藻硫化多糖的复杂单糖成分使其在食品和制药领域具有广阔的应用前景。本论文探讨了来自交替单胞菌的假定的绿藻硫化多糖裂解酶。KUL_42。我们表达并纯化了蛋白质，进行了一系列表征，信号肽已被去除。结果表明，ULA-2的蛋白分子量为53.97 kDa，在45℃、pH 8.0的Tris-HCl缓冲液中具有最高的催化活性。Km 和Vmax 值分别为2.24 mg·mL-1 和2.048 μmol·min-1·mL-1。ULA-2的活性在20~30℃时能够维持80%以上。ESI-MS分析表明初级终产物主要为二糖至四糖。ULA-2的研究丰富了绿藻硫化多糖裂解酶库，促进了石莼资源的开发和高值化利用，有利于绿藻硫化多糖裂解酶在石莼低聚糖方面的进一步研究应用。