Isolation and Characterization of Arylesterase from Root of Ginger (Zingeber)

The research was concerned with the isolation of arylesterase from the aqueous extract of Ginger using different biochemical techniques. It was shown that, using gel filtration chromatography on sephadex G-75, the solution of the proteinous precipitate produced by acetone precipitation, contained three proteinous peaks. The first two peaks (A and B) possessed a variable activity of arylesterase, where maximum specific activity was obtained in the second peak(B) which showed (22.04) folds of purification while the first peak (A) showed less activity with (16.73) folds of purification. Furthermore, the comparative molecular weight of the partially purified arylesterase (peak B) using gel filtration was found to be (46370) Dalton. The research was also concerned with finding the optimum conditions of arylesterase. Maximum activity was obtained using (9 mM) Tris HCl as a buffer at pH (6), with incubation temperature (45C), incubation time of (15min) and (3.5mM) of phenyl acetate as a substrate. Using linweaver Burk plot, it was found that maximum velocity (Vmax) and Michaelis constant (Km) had the values of (209.3 U/ml) and (1.35 mM) respectively. The effect of some chemical compounds on arylesterase activity was also studied. It was found that sodium chloride showed a competitive inhibition on the activity of the enzyme at a concentration of (4.5 mM) using Tris-HCl (9 mM) as a buffer.