Partial Separation and Some Kinetic Studies of Glutathione S-transferase (GST) in Amniotic fluid

Abstract

The research includes the isolation of glutathione S-transferase from the amniotic fluid of normal pregnancy at 40 week, studying the factors effecting the activity of the enzyme and determination of its molecular weight. Four bands components had been isolated by gel filtration chromatography from the proteinous supernatant produced by ammonium sulfate saturation after dialysis. It was found that the third peak had a high activity for the enzyme. The apparent molecular weight of the isolated enzyme using gel filtration chromatography was (22787) Dalton.The results also showed that the optimum conditions of glutathione S-transferrase were obtained at (40µg/ml) of enzyme concentration using (13.5 mmol/l) of 1-chloro-2,4-dinitrobenzene (CDNB) as a substrate, phosphate buffer (0.09 mol/l) as a buffer at pH (6.4) for (14) minutes at (25C). Using lineweaver–Burk plot, the values of maximum velocity (Vmax) and Michaelis constant (Km) were (0.76 µmol/ min) and (13.3 mmol/l) respectively. The study showed the effect of some inhibitors on the enzyme activity. Benzyl chloride possessed a noncompetitive inhibition for the enzyme at a concentration of (30 mmol/l).