Characterization of a novel bifunctional mannuronan C-5 epimerase and alginate lyase from Pseudomonas mendocina. sp. DICP-70.

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.