Identification and characterization of cellouronate (β-1,4-linked polyglucuronic acid) lyase from the scallop Mizuhopecten yessoensis

The semisynthetic polysaccharide cellouronate is a β-1,4-linked polyglucuronic acid prepared from regenerated cellulose by chemical oxidation. Here, we isolated a novel enzyme, MyAly, as a cellouronate lyase from a scallop Mizuhopecten yessoensis. Its optimum temperature, pH, and NaCl concentration for cellouronate degradation were determined to be 30 °C, 6.9, and 200–500 mM, respectively. MyAly endolytically degraded cellouronate into unsaturated di-, tri-, and tetrasaccharides with kcat of 31.1 s−1. MyAly also showed an alginate-degradation activity with a kcat value of 0.58 s−1. However, there was no significant difference in Km values between cellouronate and alginate. MyAly consisted of 280 amino acids and shared 36.5–44.1 % identity with known marine gastropod alginate lyases belonging to the polysaccharide lyase family 14. This is the first study to identify and characterize a cellouronate-degrading lyase from a marine organism, providing a better understanding of the biodegradability of the industrially important polysaccharide, cellouronate, in marine environments.