The invention provides a conversion and extraction method for producing
levodopa by an
enzyme method. The method comprises the following steps of 1, preparing
tyrosine phenol lyase, that is, centrifuging and collecting
escherichia coli by a
fermentation liquid, resuspending thalli by using a
phosphate buffer solution, and carrying out wall breaking treatment through a high-pressure
homogenizer; passing a wall-breaking liquid through a
ceramic membrane, removing
thallus fragments, and collecting filtrate; passing the filtrate through an
ultrafiltration membrane, removing small-molecule impurities in the cells, and collecting
entrapment liquid; and treating the retentate through decolorization resin, and collecting the
effluent to obtain the
tyrosine phenol lyase; 2, producing
levodopa through enzymatic conversion, adding
tyrosine phenol lyase into a
reaction system based on 3000-10000U / L, adding a reaction
bed charge, and supplementing
catechol,
sodium pyruvate and
ammonium chloride inthe conversion process in different patches, wherein the yield of
levodopa in the conversion liquid is 120-150g / L; and 3, carrying out extraction of levodopa, that is, adjusting the pH of the conversion liquid to be 3-4, and performing standing for 8-16h at a temperature of 4-8 DEG C; carrying out
centrifugation collection of
precipitation, carrying out pulping by 5-10 times of pure water and thencarrying out suction
filtration, and repeating the steps for 2-5 times; eluting crystals by ethyl
alcohol for 1-5 times and performing suction
filtration to a dry state; and placing the crystals at atemperature of 40-80 DEG C and performing
drying 1-4h to obtain a levodopa. The content of the levodopa reaches 98% or above, and the total yield reaches 80% or above.