Isolation and partial purification of thymidlit synthease enzyme from Calus lettuce plant (Lactuca sativa, L.)

ABSTRACT Callus from hypocotyl explants of lettuce (Lactuce sativa , L.) was initiated on a modified Murashige and Skoog medium containing 1.0 mg/l of benzyladenine (BA) and naphthalene acetic acid (NAA)as growth factors. Thymidylate synthase (EC 2 . 1 . 1 . 45) was found in lettuce callus and purified about 100 fold treatment by ethanol and chloroform , ammonium sulfate and gel filtration on sephadex G 150. Some properties of the partial purified enzyme from callus were investigated . The molecular weight was found to be a round 30000 D. The partially purified enzyme has an optimum pH of 6.8 with 50 mM potassium phosphate buffer with incubation temperature 30C. The Michaelis - Menten constant for deoxyuridinemonophosphate (dUMP) was 1-0510-5M and for tetrahydrofolate (THF) 3.339 10-3M . (Lactuce sativa , L.) 1.0 / . (TS) 100 . G 150 . , 30000 6.8 50 30 . (Km) 1.05 -510 3.339 -310 .