An Ke, Shi Xiaochong, Cui Fangyuan, Cheng Jingguang, Liu Na, Zhao Xia, Zhang Xiao-Hua
College of Marine Life Sciences, Ocean University of China, Qingdao 266003, China.
College of Marine Life Sciences, Ocean University of China, Qingdao 266003, China.
Protein Expr Purif. 2018 Mar;143:1-8. doi: 10.1016/j.pep.2017.10.002. Epub 2017 Oct 3.
Agar, usually extracted from seaweed, has a wide variety of industrial applications due to its gelling and stabilizing characteristics. Agarases are the enzymes which hydrolyze agar into agar oligosaccharides. The produced agar oligosaccharides have been widely used in cosmetic, food, and medical fields due to their biological functions. A beta-agarase gene, YM01-1, was cloned and expressed from a marine bacterium Catenovulum agarivorans YM01. The encoding agarase of YM01-1 consisted of 331 amino acids with an apparent molecular mass of 37.7 kDa and a 23-amino-acids signal peptide. YM01-1 belongs to glycoside hydrolase 16 (GH16) family based on the amino acid sequence homology. The optimum pH and temperature for its activity was 7.0 and 50 °C, respectively. YM01-1 was stable at a pH of pH 6.0-9.0 and temperatures below 45 °C. Thin layer chromatography (TLC) and ion trap mass spectrometer of the YM01-1 hydrolysis products displayed that YM01-1 was an endo-type β-agarase and degrades agarose, neoagarohexaose, neoagarotetraose into neoagarobiose. The K, V, K and K/K values of the YM01-1 for agarose were 8.69 mg/ml, 4.35 × 10 U/mg, 2.4 × 10 s and 2.7 × 10 s M, respectively. Hence, the enzyme with high agarolytic activity and single end product was different from other GH16 agarases, which has potential applications for the production of oligosaccharides with remarkable activities.
琼脂通常从海藻中提取,因其具有胶凝和稳定特性而在多种工业应用中广泛使用。琼脂酶是将琼脂水解为琼脂寡糖的酶。所产生的琼脂寡糖因其生物学功能已广泛应用于化妆品、食品和医学领域。从海洋细菌食琼脂链环菌YM01中克隆并表达了一个β-琼脂酶基因YM01-1。YM01-1的编码琼脂酶由331个氨基酸组成,表观分子量为37.7 kDa,含有一个23个氨基酸的信号肽。基于氨基酸序列同源性,YM01-1属于糖苷水解酶16(GH16)家族。其活性的最适pH和温度分别为7.0和50℃。YM01-1在pH 6.0 - 9.0和45℃以下的温度下稳定。YM01-1水解产物的薄层色谱(TLC)和离子阱质谱显示,YM01-1是一种内切型β-琼脂酶,可将琼脂糖、新琼脂六糖、新琼脂四糖降解为新琼脂二糖。YM01-1对琼脂糖的Km、Vmax、Kcat和Kcat/Km值分别为8.69 mg/ml、4.35×10³U/mg、2.4×10³s⁻¹和2.7×10³s⁻¹M⁻¹。因此,这种具有高琼脂分解活性和单一终产物的酶与其他GH16琼脂酶不同,在生产具有显著活性的寡糖方面具有潜在应用价值。