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A Review on L-Asparaginase
Published in Se-Kwon Kim, Marine Biochemistry, 2023
The irreversible conversion of blood glutamine into glutamic acid and ammonia is because of the presence of glutaminase activity of asparaginase. The resulting glutamate reacts with sodium in blood and gives rise to the production of monosodium glutamate (Kurtzberg et al., 2003). There are reports suggesting that due to the presence of glutaminase activity of asparaginase, leukemia patients suffer from many life-threatening side effects, such as leucopenia, acute pancreatitis, immunosuppression, hyperglycemia, thromboembolysis and neurological seizures (Devi et al.,2012; Ramya et al.,2012). Therefore, it is necessary to make a search for glutaminase-free asparaginase from the native microorganisms. In the control of leukemia, the pharmacodynamics of asparaginase differs by formulation (Pinheiro and Boos, 2004). The treatment mainly depends on the intensity of the dose and duration of the treatment of asparaginase rather than the type of asparaginase used (Silverman et al., 2001; Pui and Evans, 2006). Currently, L-asparaginase obtained from Erwinia carotovora and Escherichia coli is of commercial importance. Other microbes, such as Bacillus sp., Corneybacterium glutamicum, Enterobacter sp., Pseudomonas stutzeri and others, also produce a feasible amount of enzyme. As far as fungi are concerned, Aspergillus oryzae was found to synthesis large amount of enzyme.
Epigenetic and Metabolic Alterations in Cancer Cells: Mechanisms and Therapeutic Approaches
Published in Peter Grunwald, Pharmaceutical Biocatalysis, 2020
Glutaminolysis is commonly up-regulated in cancers, where it primarily replenishes the TCA cycle. Several lines of evidence indicate that sufficient supply of glutamine-derived carbons is necessary for the accumulation of TCA cycle-derived oncometabolites such as succinate, fumarate and 2-hydroxylglutarate (Arts et al., 2016; Slaughter et al., 2016; Salamanca-Cardona et al., 2017). Glutaminase (GLS) is the rate-limiting enzyme in glutaminolysis and several GLS inhibitors including Compound 968, BPTES and CB-839 have been developed. In breast cancer cells, Compound 968 suppressed 2-hydroxylglutarate levels (Terunuma et al., 2014). BPTES has been shown to inhibit fumarate synthesis in cells (Shanware et al., 2014). Compound 968 has been reported to decrease global H3K4me3, leading to down-regulation of cancer-associated genes (Simpson et al., 2012, 2012a). Elhammali et al. (2014) identified Zaprinast as a novel GLS inhibitor that inhibits 2-hydroxylglutarate synthesis in IDH1 mutant cancers. Zaprinast markedly reversed histone H3K9me2/3 induced by mutant IDH1, suggesting that GLS is a therapeutic target for reversing mutant IDH1/2-induced epigenetic dysfunction.
Cell Physiology
Published in Wei-Shou Hu, Cell Culture Bioprocess Engineering, 2020
A large portion of glutamine is converted to glutamate by glutaminase in the cytosol or mitochondria. Glutamate in the mitochondria is converted to α-KG via glutamate dehydrogenase (GDH), which releases an ammonium and NADH. Glutamate is also converted to α-KG via an aminotransferase reaction that transfers its amino group to the receiving OAA or pyruvate, forming aspartate or alanine, respectively. α-KG then enters the TCA cycle. The aminotransferase reaction retains the amino group in an amino acid, while the dehydrogenase reaction loses the amino group to ammonium. The former is likely to be favored in proliferating cells. Through α-ketoglutarate, glutamine is a major contributor to central metabolic flux by fulfilling its anaplerotic role as discussed above. The conversion of glutamine to α-KG releases one or two ammonium, depending on the path taken (aminotransferase or glutamate dehydrogenase). The ammonium generated is excreted to the extracellular environment. The ammonium that is released from glutamine contributes to the waste metabolite accumulation.
Production, optimization, purification, characterization, and anti-cancer application of extracellular L-glutaminase produced from the marine bacterial isolate
Published in Preparative Biochemistry & Biotechnology, 2020
Hanaa Orabi, Esmail El-Fakharany, Eman Abdelkhalek, Nagwa Sidkey
The effect of L-glutaminase used in vitro cytotoxicity test was done to identify the activity of L-glutaminase in growth inhibition of three different carcinoma cell lines, HepG-2, NFS-60, MCF-7 cells, and one normal cell line, Vero cells. The obtained data revealed that L-glutaminase has a potent inhibition activity against NFS-60, MCF-7, and HepG-2 cancer cell lines and no effective inhibition on the viability of Vero cells. Thus, L-glutaminase is considered as a potent anticancer drug. The IC50 values of the purified L-glutaminase on HepG-2, NFS-60, and MCF-cells were estimated to be 17.67, 6.95, and 10.89 μg/mL with selectivity indexes (SI) equal 2.62, 6.65, and 4.24, respectively. NFS-60 cells were the most sensitive cell line for treatment with L-glutaminase followed by MCF-7 cells, then HepG-2 cells.
Optimization of culture conditions and bench-scale production of anticancer enzyme L-asparaginase by submerged fermentation from Aspergillus terreus CCT 7693
Published in Preparative Biochemistry and Biotechnology, 2019
T. A. Costa-Silva, D. I. Camacho-Córdova, G. S. Agamez-Montalvo, L. A. Parizotto, I. Sánchez-Moguel, A. Pessoa-Jr
L-asparaginase activity was determined according to Drainas and Pateman[13] and modified as follows: 1.5 mL 20 mmol·L−1 Tris-HCl buffer, pH 7.2; 0.2 mL 100 mmol·L−1 stock L-asparagine solution; 0.2 mL 1 mol·L−1 stock hydroxylamine solution; and 0.1 g biomass were mixed and incubated at 37 °C and 120 rpm. After 30 min, 0.5 mL of ferric chloride reagent [10% (w/v) FeCl3 and 5% (w/v) trichloroacetic acid in 0.66 mol·L−1 HCl] was added. One unit of L-asparaginase is the amount of enzyme that releases 1 mmol NH3 or aspartic acid per minute at 37 °C at the specific conditions just mentioned. L-glutaminase was assayed according to Imada et al.[14]. One L-glutaminase unit was defined as the amount of enzyme that liberates 1 μmol of ammonia per 1 min. The proteolytic activity assay was developed according to the method described by Charney and Tomarelli[15] using azocasein as the substrate. One unit of activity is equivalent to a change in optical density of 0.01 nm per minute at 430 nm. The Bradford method was used to quantify the total protein content.[16]