Cloning, Expression, Purification and Characterization of the β-galactosidase PoβGal35A from Penicillium oxalicum.

Galactosidases are industrially important enzymes that hydrolyze galactosidic bonds in carbohydrates. Identifying new galactosidases with distinct functional characteristics is of paramount importance. In this study, we report the finding of a novel β-galactosidase PoβGal35A from the fungus Penicillium oxalicum. PoβGal35A belongs to the glycoside hydrolase family 35 (GH35), functions optimally at 70 °C and pH 5.0, and exhibits a specific high activity (191 ± 6.2 U/mg) towards pNPβgal. Ca, Feand Ba ions enhance the activity of the enzyme, whereas Cu and Hg significantly reduce it. This enzyme releases galactose from β-1,3-galactan, β-1,4-galactan, β-1,6-galactan, as well as arabinogalactan from larchwood (LWAG). In addition, PoβGal35A acts synergistically with arabinosidase to degrade LWAG. These results suggest that PoβGal35A is a high activity exo-β-1,3/4/6-galactanase that can be used to establish glycan blocks in glycoconjugates, and thus provides a new tool for biotechnological applications.