Extraction and Purification of Extracellular L-Glutamate Oxidase from Streptomyces

The bacterial isolates Streptomyces were obtained from the soil and cultivated in a wheat bran medium, which was used to produce the L–glutamate oxidase enzyme. The extracellular enzyme was then extracted using a cooling centrifugation process to obtain the filtrate that represents the crude enzyme. Afterward, the enzyme purification processes were carried out which included precipitation with ammonium sulfate as a preliminary purification step followed by dialysis to remove the salts. Next, ion-exchange chromatography and gel filtration were used to finish the purification process, and the enzyme activity was determined for each purification step. The results of purification of L-glutamate oxidase enzyme from streptomyces using ammonium sulfate showed that the specific activity was ۸.۲۵ units/mg protein with a saturation ratio of ۶۰%. Moreover, the results of purification using a dialysis tube indicated that the specific activity was ۹.۵ units/mg protein. In addition, the result of purification using diethylaminoethyl cellulose ion column revealed that the specific activity was ۲۵ unit/mg protein and the results of purification using gel filtration showed that the specific activity was ۵۶ units/mg protein which was the best step in the purification process due to high specific activity of the enzyme. The optimum temperature and pH for the activity and stability of the enzyme were tested. Based on the findings, the optimum temperature for the activity of the enzyme was ۳۷ °C. In addition, it was found that the optimum temperature range for the stability of the enzyme was ۳۰-۵۰ °C. Besides, the optimum pH for the activity was ۷.۰ and the optimum pH range for the enzyme stability was ۵.۰-۷.۰.

کلیدواژه ها:

L-glutamate oxidase ، L-glutamate ، Streptomyces ، Specific activity