Identification And Characterization Of Cellouronate (Beta-1,4-Linked Polyglucuronic Acid) Lyase From The Scallop Mizuhopecten Yessoensis

The semisynthetic polysaccharide cellouronate is a beta-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 degrees C, 6.9, and 200-500 mM, respectively. MyAly endolytically degraded cellouronate into unsaturated di-, tri-, and tetrasaccharides with k(cat) of 31.1 s(-1). MyAly also showed an alginate-degradation activity with a k(cat) value of 0.58 s(-1). However, there was no significant difference in K-m 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.