β-Xylosidase mutant immobilization on UiO-66-NH2 for continuous production of ginsenoside Rg1 and selective production of furfural from notoginsenoside R1

In order to improve the activity and reusability of β-xylosidase, the β-xylosidase mutant S160N-R333H (R333H) which could convert notoginsenoside R1 to ginsenoside Rg1 and xylose was immobilized on the metal-organic framework (MOF) UiO-66-NH2. The physical and biochemical properties of immobilized β-xylosidase (R333H@UiO-66-NH2) were studied in detail. The results showed improved performances, i.e. the high immobilization yield of 93% and recovery activity of 192.8%, better stability under acidic or trypsin-containing conditions, the higher activity in the reaction containing ions, and the improved catalytic efficiency (was 1.37-fold than that of free R333H). Importantly, the ginsenoside Rg1 yields remained more than 80% after six recycles in McIlvaine buffer and pure water. The UiO-66-NH2 could catalyze xylose dehydration to produce furfural and the yield reached 69%. Thus this study provides a promising method for production of bioactive or platform chemicals via continuous conversion of xyloylated substrates using nanocatalyst synthesized by β-xylosidase and MOF.