Coupled reaction of glycosyltransferase and sucrose synthase for high-yielding and cost-effective synthesis of rosin

Rosin has wide applications in food and pharmaceutical fields. Herein, 96% yield of rosin was synthesized using Arabidopsis thaliana glucosyltransferase (UGT73C5) from 2 mM cinnamyl alcohol (CA) and excess UDP-glucose (UDPG). Furthermore, replacing expensive UDPG by uridine diphosphate (UDP), coupled reaction by Arabidopsis thaliana sucrose synthase (AtSUS1) and UGT73C5 led to 100% yield of rosin. In addition, crude UGT73C5 and AtSUS1 resulted in rosin yield of 95% (10 mM CA) and 94% (20 mM CA) without UDP addition. With elevated CA concentration, whole-cell catalysis led to even higher rosin yield than crude enzymes preparations with a final yield of 91% from 50 mM CA. Furthermore, in cascaded reaction with a newly introduced Catharanthus roseus glucosyltransferase (CaUGT3), rosavin B was synthesized with a yield of 62% from 50 mM CA. This developed coupled pathway provides a feasible and cost-effective approach for the production of rosin and its glucosides from CA.