Banana peel tyrosinase immobilized in agar-agar organic matrix “beads” for L-DOPA production in improvised reactors: A Box-Behnken response methodology-based approach

Tyrosinase (7.9 U/mg protein) from the banana peel ( TBp ) served as a low-cost immobilized biocatalyst for the production of 3, 4-di hydroxyphenyl-L-alanine (L-DOPA). L-DOPA, a dopamine precursor, useful in the management of Parkinson’s disease, was produced in improvised batch and packed bed reactors. L-DOPA production by the immobilized TBp was optimized via response surface methodology (RSM). L-DOPA was characterized via spectrophotometry (Arnow’s method) and thin-layer chromatography. L-DOPA productivities obtained at equimolar substrate concentrations and 500 mg of TBp for the packed bed and batch process ( BP ) were 34.0 ± 2.1 and 15.4 ± 0.9 \(\frac{mg}{L}/h\) respectively. L-DOPA was optimally produced in a batch reactor at the conditions: ascorbic acid (25 mM), tyrosine (5 mM) and enzyme amount (1000 mg). The resulting L-DOPA productivity in the BP after the Box-Behnken RSM model validation was 63 ± 3.0\(\frac{mg}{L}/h\). There was a good fit with the model obtained based on the closeness of the predicted and experimental values, R 2 (0.9979), model-F value (575.2) and the insignificant lack of fit. After four successive batch processes, about 35% loss in L-DOPA productivity was observed. In conclusion, banana peel served as a relatively cheap and easily available source of tyrosinase for the production of L-DOPA in both batch and packed bed reactors.