Dalian Engineering Research Center for Carbohydrate Agricultural Preparations, Liaoning Provincial Key Laboratory of Carbohydrates, Dalian Institute of Chemical Physics, Chinese Academy of Sciences, Dalian 116023, China; Dalian Maritime University, Dalian, China.
University of California, Berkeley, USA.
Int J Biol Macromol. 2020 May 1;150:662-670. doi: 10.1016/j.ijbiomac.2020.02.126. Epub 2020 Feb 13.
Alginate is a family of industrially important linear polymers consisting of β-D-mannuronic acid (M) and its C-5 epimer α-L-guluronic acid (G). The function of alginate is closely related to the ratio of M/G. Mannuronan C-5 epimerase, which converts M to G, is a key enzyme involved in the biosynthesis of alginate. A new mannuronan C-5 epimerase isolated from Pseudomonas mendocina. sp. DICP-70 named PmC5A was characterized in this study. From the H NMR analysis of the products, we have found that PmC5A possesses alginate lyase function in addition to mannuronan C-5-epimerase. The optimal pH and temperature of lyase and epimerase were found to be 8.0, 9.0 and 40 °C, 30 °C, respectively. PmC5A also shows lyase activity toward PolyMG and G-blocks.
藻酸盐是一类由β-D-甘露糖酸（M）及其 C-5 差向异构体α-L-古罗糖醛酸（G）组成的工业上重要的线性聚合物家族。藻酸盐的功能与其 M/G 比密切相关。将 M 转化为 G 的藻酸盐 C-5 差向异构酶是参与藻酸盐生物合成的关键酶。本研究从假单胞菌属 Mendocina。sp。DICP-70 中分离到一种新的 M 聚糖 C-5 差向异构酶，命名为 PmC5A。通过对产物的 1H NMR 分析，我们发现 PmC5A 除了具有 M 聚糖 C-5-差向异构酶活性外，还具有藻酸盐裂解酶活性。酶和差向异构酶的最适 pH 和温度分别为 8.0、9.0 和 40°C、30°C。PmC5A 对 PolyMG 和 G 块也表现出裂解酶活性。
