الملخص

ABSTRACT Callus induction occurred on stem segments of Nigella sativa L. seedlings grown on a modified Murashige and Skoog medium containing 10-6 M of 2, 4- dichlorophenoxy acetic acid (2, 4 – D). Glutamine synthetase (EC 6. 3 . 1. 2) was isolated and partially purified from Nigella sativa L. callus the partially purified enzyme from the aqueous extract by ammonium sulfate precipitation, dialysis and gel filtration on sephadex G – 200 revealed that the activity increased by 37 fold. The molecular weight by gel – filtration chromatography was found to be around 50000 Da. The optimum conditions of the partially purified glutamine synthetase from callus were obtained by using Tris – HCl (80 mM) at pH 2.7 as a buffer and 10 mM of glutamate as substrate with incubation temperature 30° C. The Michaelis Menten constants for glutamate, adenosinetriphophate and ammonium chloride were 10 × 10-3M, 2 × 10-3 M and 0.280 × 10-3 M respectively.