Protuberic Acid-Hydrolytic Enzyme in Kobayasia nipponica and Characterization of the Hydrolytic Products

When the cold water-extract of Kobayasia nipponica containing a glycuronan, protuberic acid (PA), was allowed to stand at room temperature, PA was hydrolyzed. The optimum conditions for this PA-hydrolysis were 37°C and pH 4–5 in 0.1 M acetate buffer. Characterization of the hydrolytic products was performed by chemical analysis, and by 1H- and 13C-NMR spectroscopy. They were identified as D-GlcUA and O-(α-L-IdUAp)-(l-4)-D-GlcUA. These results suggest that PA-hydrolytic enzyme(s) include at least endo-β-D-glucuronidase.