Synthesis of (R)-acetoin by targeted immobilization of acetolactate synthase and acetolactate decarboxylase via the spy/snoop system

Abstract

Acetoin (3-hydroxy-2-butanone) is an important four-carbon platform compound and an intermediate for several high-value-added pharmaceutical compounds. In this study, Catcher-Tag tagged proteins were used for targeted immobilization of acetolactate synthase (ALS) and acetolactate decarboxylase (ALDC) for catalyzing the synthesis of Acetoin from sodium pyruvate in vitro. The study discussed the enzymatic properties of the immobilized enzyme LX@ALS-SpyTag 和 LX@ALDC-SnoopTag, as well as the optimal catalytic conditions and reusability of the immobilized dual enzyme in vitro catalytic system. The immobilized enzyme exhibited higher relative activity across a broader range of temperature and pH intervals than the free enzyme. The in vitro catalytic synthesis of (R)-acetoin from sodium pyruvate using an immobilized dual enzyme system resulted in 99.95 % of the theoretical conversion of (R)-acetoin at 45°C, pH 7.0, and 0.2 M substrate concentration. In addition, the immobilized dual enzyme system had better operational stability than the free enzyme, retaining 69.20 % of the initial total catalytic activity after 5 cycles. In conclusion, this study demonstrated a promising and convenient Catcher-Tag tagged protein immobilization strategy that enables rapid targeted immobilization of tagged proteins directly from crude enzyme solution, providing a novel approach for the construction of in vitro immobilized multi-enzyme complexes.