Purification and characterization of a highly alkaline pectin lyase from Fusarium lateritum MTCC 8794

A highly alkaline pectin lyase (PNL) produced by Fusarium lateritum MTCC 8794 using solid-state fermentation was purified and biochemically characterized. The enzyme was purified to homogeneity by comparatively simple method involving ammonium sulfate precipitation and cation exchange chromatography resulting in a final purification fold of 5.5 with specific activity of 1.9 U/mg and yield of 3.42%. The SDS-PAGE of the purified enzyme revealed a single protein band of approximately 16 kDa. The pH optimum was found to be 10.0, while the enzyme was stable in the pH range 6.0-10.0. The optimum temperature of the purified PNL was 40 °C, the enzyme being stable upto 50 °C for 30 min. The K_m value calculated by Michaelis-Menten curve was found to be 0.79 mg/mL, while V_max and k_cat of the purified enzyme were found to be 0.57 international unit and 41.6 s^-1, respectively. The enzyme showed inhibition by most of the divalent cations at 1 mM concentration.