Purification, Kinetic Properties and Antitumor Activity of L-Glutaminase from Penicillium brevicompactum NRC 829

Abstract

Aim: The aims of the present study were to purify and characterize L-glutaminase from Penicillium brevicompactum NRC 829; and to evaluate the antitumor activity of the purified enzyme against different tumor human cell lines. Study Design: Testing of antitumor activity of L-glutaminase, purified from a filamentous fungal strain, against four different tumor human cell lines. Place and Duration of Study: Department of Microbial Chemistry, Genetic Engineering and Biotechnology Division, National Research Centre (NRC), Cairo, Egypt, between January 2011 and February 2012. Methodology: P. brevicompactum NRC 829 was grown and maintained on modified Czapek Dox agar (MCD) medium. Cell-free extract was directly used as the source of crude enzyme. L-glutaminase was purified by heat treatment for 20 min at 50ºC, followed by gel filtration on Sephadex G-100 and G-200 columns. Results: An intracellular L-glutaminase from Penicillium brevicompactum NRC 829 was purified to homogeneity (162.75 fold) with an apparent molecular mass (Mr) of 71 kDa. The purified enzyme showed its maximal activity against L-glutamine when incubated at pH 8.5 at 50ºC for 30 min. The purified enzyme retained about 92 % of its initial activity after incubation at 70ºC for 30 min indicating the thermo-stability nature of this enzyme. The highest activity was reported towards its natural substrate, L-glutamine, with an apparent Km value of 1.66 mM. The purified enzyme inhibited the growth of human cell line hepatocellular carcinoma (Hep-G2), with IC50 value of 63.3μg/ml. Conclusion: L-glutaminase purified from Penicillium brevicompactum NRC 829 is a potential candidate in food and pharmaceutical industries.