ABSTRACT
Abstract L-glutaminase was produced by Streptomyces canarius FR (KC460654) with an apparent molecular mass of 44 kDa. It has 17.9 purification fold with a final specific activity 132.2 U/mg proteins and 28% yield recovery. The purified L-glutaminase showed a maximal activity against L-glutamine when incubated at pH 8.0 at 40 °C for 30 min. It maintained its stability at wide range of pH from 5.0 11.0 and thermal stable up to 60 °C with Tm value 57.5 °C. It has high affinity and catalytic activity for L-glutamine (Km 0.129 mM, Vmax 2.02 U/mg/min), followed by L-asparagine and L-aspartic acid. In vivo, L-glutaminase showed no observed changes in liver; kidney functions; hematological parameters and slight effect on RBCs and level of platelets after 10 days of rabbit's injection. The anticancer activity of L-glutaminase was also tested against five types of human cancer cell lines using MTT assay in vitro. L-glutaminase has a significant efficiency against Hep-G2 cell (IC50, 6.8 μg/mL) and HeLa cells (IC50, 8.3 μg/mL), while the growth of MCF-7 cells was not affected. L-glutaminase has a moderate cytotoxic effect against HCT-116 cell (IC50, 64.7 μg/mL) and RAW 264.7 cell (IC50, 59.3 μg/mL).
Subject(s)
Animals/chemistry , Animals/drug effects , Animals/enzymology , Animals/metabolism , Animals/pharmacology , Antineoplastic Agents/chemistry , Antineoplastic Agents/drug effects , Antineoplastic Agents/enzymology , Antineoplastic Agents/metabolism , Antineoplastic Agents/pharmacology , Biocatalysis/chemistry , Biocatalysis/drug effects , Biocatalysis/enzymology , Biocatalysis/metabolism , Biocatalysis/pharmacology , Cell Proliferation/chemistry , Cell Proliferation/drug effects , Cell Proliferation/enzymology , Cell Proliferation/metabolism , Cell Proliferation/pharmacology , Enzyme Stability/chemistry , Enzyme Stability/drug effects , Enzyme Stability/enzymology , Enzyme Stability/metabolism , Enzyme Stability/pharmacology , Glutaminase/chemistry , Glutaminase/drug effects , Glutaminase/enzymology , Glutaminase/metabolism , Glutaminase/pharmacology , Glutamine/chemistry , Glutamine/drug effects , Glutamine/enzymology , Glutamine/metabolism , Glutamine/pharmacology , HeLa Cells/chemistry , HeLa Cells/drug effects , HeLa Cells/enzymology , HeLa Cells/metabolism , HeLa Cells/pharmacology , /chemistry , /drug effects , /enzymology , /metabolism , /pharmacology , Humans/chemistry , Humans/drug effects , Humans/enzymology , Humans/metabolism , Humans/pharmacology , Kinetics/chemistry , Kinetics/drug effects , Kinetics/enzymology , Kinetics/metabolism , Kinetics/pharmacology , Streptomyces/chemistry , Streptomyces/drug effects , Streptomyces/enzymology , Streptomyces/metabolism , Streptomyces/pharmacology , Substrate Specificity/chemistry , Substrate Specificity/drug effects , Substrate Specificity/enzymology , Substrate Specificity/metabolism , Substrate Specificity/pharmacologyABSTRACT
Thymidine kinase is a key enzyme responsible for the activation of several anticancer and antiviral drugs. As the first enzyme in the salvage pathway of thymidine, it is regulated by the feedback inhibition exerted by the end-product of the pathway, namely thymidine 5'-triphosphate. 5'-Aminothymidine is a non-toxic analogue of thymidine capable of interfering with this regulatory mechanism. In fact, it has been shown that 5'-aminothymidine increases the cytotoxicity and metabolism of various thymidine analogues currently in use of the clinic as antineoplastic agents. This mini-review article focuses in the evidence supporting the role of 5'-aminothymidine as a potential prototype drug for a new class of anticancer agents: drugs which affect the regulation of key metabolic pathways that determine the efficacy of agents with cytotoxic activity. The mechanism of action, antineoplastic activities and basis for selectivity in tissue culture models are also described