The invention provides a method for enzymatically synthesizing
astragalin. The method comprises the following steps that 1, key enzymes needed in the synthesizing process of
astragalin are cloned, expressed and purified, wherein the key enzymes comprise
glycogen phosphorylase GP, glucose pyrophosphorylase GalU,
flavanone-3-hydroxylase F3H,
flavanone synthase FLS1 and
flavonoid3-O-glucanotransferase UGT78K2; 2,
glycogen Gn is synthesized into glucose-1-
phosphoric acid G-1-P under the GP effect; 3, G-1-P is synthesized into
uridine diphosphate UDPG under the GalU effect; 4,
naringenin NRN is synthesized into dihydro
kaempferol DHK under the F3H effect; 5, DHK is synthesized into
kaempferol KMF under the FLS1 effect; 6, KMF and UDPG are synthesized into
astragalin under the UGT78K2 effect. According to the method, few steps are adopted, the operation condition is mild, few side products are generated, the yield is large,
pollution is avoided, and the production cost is remarkably reduced.