Production of L-DOPA from pyrocatechol and DL-serine by bioconversion using immobilized Erwinia herbicola cells

Purification and characterization of tyrosine phenol lyase from Citrobacter freundii

The purification and characterization of intracellular tyrosine phenol lyase from Citrobacter freundii has been carried out. The enzyme was purified 35-fold to homogeneity by ammonium sulphate precipitation and hydrophobic interaction chromatography. Its subunit molecular weight was found to be 52 kDa on sodium dodecyl sulphate polyacrylamide gel electrophoresis. The purified tyrosine phenol lyase showed maximum activity in borate buffer (0.05 M at pH 8.5) at 45 °C after 20 min of incubation. The Km and Vmax values of purified enzyme were found to be 0.446 mm and 0.342 mM/min/mg. This enzyme exhibits t1/2 of 10, 52 and 130 min at 55, 45 and 35 °C, respectively. The N-terminal amino acid sequence was determined as MET-ASN-TYR-PRO-ALA-GLU-PRO-PHE-ARG-ILETRP- TRP-VAL-GLY.

Optimization of process parameters for the production of tyrosine phenol lyase by Citrobacterfreundii MTCC 2424

The process optimization using technological combinations for the production of tyrosine phenol lyase by Citrobacter freundii MTCC 2424 has been carried out in this study. The maximum production of tyrosine phenol lyase (0.15 U) was obtained by culturing C. freundii MTCC 2424 in a medium containing (g/l) meat extract 5.0, yeast extract 5.0, peptone 2.5, and l-tyrosine 1.0 at 25 degrees C for 16 h in a temperature controlled orbital shaker. A 2.5-fold increase in enzyme activity with 1.3-fold decrease in the cost of enzyme production (in terms of media components) was achieved by using different technological combinations. The process optimization using technological combinations allowed quick optimization of large number of variables, which helps in designing of suitable fermentation conditions for the cost-effective production of tyrosine phenol lyase. Moreover, this also provides information for balancing the nutrient concentration with minimum experimentation.