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Purification and Characterization of Glutaminase Free Asparaginase from Enterobacter cloacae: In-Vitro Evaluation of Cytotoxic Potential against Human Myeloid Leukemia HL-60 Cells.

ABSTRACT: Asparaginase is an important antileukemic agent extensively used worldwide but the intrinsic glutaminase activity of this enzymatic drug is responsible for serious life threatening side effects. Hence, glutaminase free asparaginase is much needed for upgradation of therapeutic index of asparaginase therapy. In the present study, glutaminase free asparaginase produced from Enterobacter cloacae was purified to apparent homogeneity. The purified enzyme was found to be homodimer of approximately 106 kDa with monomeric size of approximately 52 kDa and pI 4.5. Purified enzyme showed optimum activity between pH 7-8 and temperature 35-40°C, which is close to the internal environment of human body. Monovalent cations such as Na+ and K+ enhanced asparaginase activity whereas divalent and trivalent cations, Ca2+, Mg2+, Zn2+, Mn2+, and Fe3+ inhibited the enzyme activity. Kinetic parameters Km, Vmax and Kcat of purified enzyme were found to be 1.58×10-3 M, 2.22 IU ?g-1 and 5.3 × 104 S-1, respectively. Purified enzyme showed prolonged in vitro serum (T1/2 = ~ 39 h) and trypsin (T1/2 = ~ 32 min) half life, which is therapeutically remarkable feature. The cytotoxic activity of enzyme was examined against a panel of human cancer cell lines, HL-60, MOLT-4, MDA-MB-231 and T47D, and highest cytotoxicity observed against HL-60 cells (IC50 ~ 3.1 IU ml-1), which was comparable to commercial asparaginase. Cell and nuclear morphological studies of HL-60 cells showed that on treatment with purified asparaginase symptoms of apoptosis were increased in dose dependent manner. Cell cycle progression analysis indicates that enzyme induces apoptosis by cell cycle arrest in G0/G1 phase. Mitochondrial membrane potential loss showed that enzyme also triggers the mitochondrial pathway of apoptosis. Furthermore, the enzyme was found to be nontoxic for human noncancerous cells FR-2 and nonhemolytic for human erythrocytes.

SUBMITTER: Husain I

PROVIDER: S-EPMC4758734 | biostudies-literature | 2016

REPOSITORIES: biostudies-literature

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Purification and Characterization of Glutaminase Free Asparaginase from Enterobacter cloacae: In-Vitro Evaluation of Cytotoxic Potential against Human Myeloid Leukemia HL-60 Cells.

Husain Islam I Sharma Anjana A Kumar Suresh S Malik Fayaz F

PloS one 20160218 2

Asparaginase is an important antileukemic agent extensively used worldwide but the intrinsic glutaminase activity of this enzymatic drug is responsible for serious life threatening side effects. Hence, glutaminase free asparaginase is much needed for upgradation of therapeutic index of asparaginase therapy. In the present study, glutaminase free asparaginase produced from Enterobacter cloacae was purified to apparent homogeneity. The purified enzyme was found to be homodimer of approximately 106 ...[more]

PMID: 26891220

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Project description:The traditional medicine Dingqing Tablet produces effective efficacy in treating acute myeloid leukemia, but its specific mechanism remains to be investigated. Dingqing Tablet consists of Codonopsis, Indigo Naturalis, Cortex Moutan, Radix Notoginseng, Citrus Reticulata, and Eolite. The active components of Dingqing Tablets were screened by the TCMSP database. Meanwhile, the SwissTargetPrediction database was utilized to predict the corresponding targets. Relevant disease targets of acute myeloid leukemia were obtained from GeneCards. The obtained targets of Dingqing Tablets and genes of acute myeloid leukemia were used, and the overlapped genes were presented in the Venn diagram. A drug-component-target network was constructed via Cytoscape 3.6.0 software. Molecular docking methodology was also used with AutoDock Vina 1.1.2. Furthermore, the effects of kaempferol on the proliferation and apoptosis of HL-60 cells were identified using 3-(4,5)-dimethylthiahiazo(-z-y1)-3,5-di-phenytetrazoliumromide (MTT), 5-Ethynyl-2'-deoxyuridine (EDU), flow cytometry, and TdT-mediated dUTP nick-end labeling (TUNEL) assays. The combination of kaempferol and AKT1 was verified using an immunoprecipitation (IP) experiment and the effects of Kaempferol on HL-60 cell apoptosis by western blot (WB) and qPCR. The key component kaempferol and the core target gene AKT1 were sorted out using a drug-component target network diagram. Molecular docking results revealed that the binding energy between kaempferol and AKT1 was lower than -5 kcal/mol. MTT and EDU assays indicated that kaempferol markedly inhibited the proliferation of HL-60 cells. Flow cytometry and TUNEL assays suggested that kaempferol substantially promoted HL-60 cell apoptosis. IP assay results testified that kaempferol could bind to AKT1, thereby reducing the level of P-AKT and promoting HL-60 cell apoptosis. The monomer kaempferol of Dingqing Tablet could promote apoptosis of HL-60 cells, and the mechanism might correlate with the combination of kaempferol and AKT1, reducing the level of P-AKT and promoting the expression of the apoptotic signaling pathway.

Dataset Information

Purification and Characterization of Glutaminase Free Asparaginase from Enterobacter cloacae: In-Vitro Evaluation of Cytotoxic Potential against Human Myeloid Leukemia HL-60 Cells.

Publications

Purification and Characterization of Glutaminase Free Asparaginase from Enterobacter cloacae: In-Vitro Evaluation of Cytotoxic Potential against Human Myeloid Leukemia HL-60 Cells.

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