Antitumor activity of L-asparaginase from Thermus thermophilus

L-Asparaginase (EC 3.5.1.1) was purified to homogeneity from Thermus thermo philus. The apparent molecular mass of L-asparaginase was found to be 33 kD a by SDS-PAGE, whereas by Sephacryl S-300 superfine column it was found to be 200 kDa, indicating that the enzyme in the native stage acts as hexamer, It is a thermostable enzyme and keeps all of its activity at 80 degreesC f or 10 min. The antiproliferative activity of the purified L-asparaginase fr om T. thermiphilos was tested against the following human cell lines: K-562 (chronic myelogenous leukemia), Rail (Burkitt's lymphoma), SK-NMC (primiti ve neuroectodermal tumor), HeLa (cervical cancer), BT20 and MCF7 (breast ca ncers), HT-29 (human colon cancer), and OAW-42 (ovarian cancer). The antipr oliferative activity of T. thermophilus enzyme was compared with Erwinase, the commercially available L-asparaginase from Erwinia corotovora. The pote ncy difference between the two L-asparaginases was greater in HeLa and SK-N -MC than in other cell lines. The fact that L-asparaginase from T. thermoph ilus does not hydrolyse L-glutamine makes it advantageous for future clinic al trials. [(C) 2001 Lippincott Williams & Wilkins.].