Characterization of a GH43 Bifunctional Glycosidase from Endophytic Chaetomium globosum and Its Potential Application in the Biotransformation of Ginsenosides.

The GH43 family of glycosidases represents an important class of industrial enzymes that are widely utilized across the food, pharmaceutical, and various other sectors. In this study, we identified a GH43 family glycoside hydrolytic enzyme, Xyaf313, derived from the plant endophytic fungus Chaetomium globosum DX-THS3, which is capable of transforming several common ginsenosides. The enzyme function analysis reveals that Xyaf313 exhibits dual functionality, displaying both α-L-arabinofuranosidase and β-D-xylosidase activity. When acting as an α-L-arabinofuranosidase, Xyaf313 achieves optimal enzyme activity of 23.96 U/mg at a temperature of 50 °C and a pH of 7. In contrast, its β-D-xylosidase activity results in a slight reduction in enzyme activity to 23.24 U/mg, with similar optimal temperature and pH conditions to those observed for the α-L-arabinofuranosidase activity. Furthermore, Xyaf313 demonstrates considerable resistance to most metal ions and common chemical reagents. Notably, while the maximum enzyme activity of Xyaf313 occurs at 50 °C, it maintains high activity at room temperature (30 °C), with relative enzyme activity exceeding 90%. Measurements of ginsenoside transformation show that Xyaf313 can convert common ginsenosides Rc, Rb₁, Rb₂, and Rb₃ into Rd, underscoring its potential for pharmaceutical applications. Overall, our findings contribute to the identification of a new class of bifunctional GH43 glycoside hydrolases, highlight the significance of plant endophytic fungi as a promising resource for the screening of carbohydrate-decomposing enzymes, and present new candidate enzymes for the biotransformation of ginsenosides.