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Mammalian Cell Physiology
Published in Anthony S. Lubiniecki, Large-Scale Mammalian Cell Culture Technology, 2018
Figure 2 illustrates some of the primary routes of glutamine metabolism in animal cells. No attempt has been made to assign sub-cellular compartments for the various reactions, although glutaminase activity seems to be associated with the mitochondria in many cells (151, 154, 155). Glutamine carbon enters the TCA cycle as α-ketoglutarate, formed either through transamination reactions as discussed earlier or through an oxidative deamination step catalyzed by glutamate dehydrogenase. Aminotransferases or transamination reactions are believed to be the major route for the second step in glutamine utilization in lymphocytes (156), intestinal cells (138, 139), and tumor cells (157). As seen in Fig. 2, the major products from transamination reactions involving glutamate (which originates from glutamine) are alanine and aspartate. As previously discussed, the formation of these products will be dependent on the relative abundance of alanine transaminase or aspartate transaminase present in a cell line or tissue.
Catabolite Regulation of the Main Metabolism
Published in Kazuyuki Shimizu, Metabolic Regulation and Metabolic Engineering for Biofuel and Biochemical Production, 2017
The growth of Human tumor cells is driven by MYC oncogene, and sensitive to glutamin (Gln) metabolism or glutaminolysis (Yuneva et al. 2007), where glutamin transported by glutamine transporter is converted to glutamate (Glu) by glutaminase, and in turn glutamate is converted to αKG in the TCA cycle. In this reaction, NADPH and NH3 are produced, where NH3 is excreted as waste. Lipid synthesis is made from citrate in the proliferating cell, where OAA is limiting for citrate formation, and thus OAA must be replenished by anaplerosis. Although Pyc may play a role for this, it may be minor. Instead, the glutamine-dependent anaplerosis plays an important role. As mentioned above, glutamine can be converted to αKG in the cytosol as well as in the mitochondria, and αKG in the cytosol can enter into the mitochondria. The mitochondrial glutamate can be converted to αKG by glutamate dehydrogenase (GDH). This αKG is converted to replenish OAA via part of the TCA cycle. Glutamine carbon is converted to lactate by glutaminolysis (deBerardinis et al. 2008). In the case where glutamine is limited, the anaplerosis by the above pathway is limited, and the anaplerosis is mainly made by Pyc from glucose (Cheng et al. 2011).
Toxic effects of Aroclor 1254 on rat liver and modifying roles of selenium
Published in International Journal of Environmental Health Research, 2023
Aylin Balcı Özyurt, Pınar Erkekoğlu, Naciye Dilara Zeybek, Ali Aşcı, Ünzile Yaman, Ofcan Oflaz, Murat Kızılgün, Evin İşcan, Tuğçe Batur, Mehmet Öztürk, Belma Koçer-Gümüşel
Blood urea nitrogen (BUN), total bilirubin and creatinine levels were measured by an automatic analyzer (Beckman Coulter, Inc., Brea, CA, USA). While measuring BUN, urea is hydrolyzed enzymatically by urease to yield ammonia and carbon dioxide. The ammonia and α-oxoglutarate are converted to glutamate in a reaction catalyzed by L-glutamate dehydrogenase (GLDH). Simultaneously, a molar equivalent of reduced NADH is oxidized.3,4,5 Two molecules of NADH are oxidized for each molecule of urea hydrolyzed. The rate of change in absorbance at 340 nm, due to the disappearance of NADH, is directly proportional to the BUN concentration in the sample. For the measurement of total bilirubin, a stabilized diazonium salt, 3,5-dichlorophenyldiazonium tetrafluoroborate (DPD) that reacts with bilirubin to form azobilirubin was used. Caffeine and a surfactant are used as reaction accelerators. The absorbance at 570/660 nm is proportional to the bilirubin concentration in the sample. A separate serum blank is performed to eliminate endogenous plasma interferences. In the creatinine measurements, picric acid, which reacts with creatinine at alkaline pH to form a yellow-orange complex was used. The rate of change in absorbance at 520/800 nm is proportional to the creatinine concentration in the sample.
Enhancing the production of poly-γ-glutamate in Bacillus subtilis ZJS18 by the heat- and osmotic shock and its mechanism
Published in Preparative Biochemistry & Biotechnology, 2020
Yichao Song, Yishu Zhang, Min He, Hang Liu, Chunyu Hu, Liuzhen Yang, Ping Yu
To date, the biosynthetic pathway of endogenous glutamate, the precursor of the γ-PGA biosynthesis, was unclear. Ashiuchi et al.[11] proposed the existence of three glutamate metabolic pathways in microorganisms: (1) glutamate dehydrogenase catalyzed the generation of glutamate from α-ketoglutaric acid and inorganic ammonia in the absence of glutamine in the medium; (2) aminotransferase catalyzed the transamination reaction of amino acids with α-ketoglutaric acid to produce glutamate; (3) when glutamine existed in the medium, glutamate synthase catalyzed the reaction of α-glutaric acid with glutamine to form glutamate. Peng et al.[35] found that the biosynthetic pathways of glutamate in B. methylotrophicus included amino acid transaminase pathway, glutamate synthase pathway and glutamine synthase pathway.
Biodegradation of cyanide to ammonia and carbon dioxide by an industrially valuable enzyme from the newly isolated Enterobacter zs
Published in Journal of Environmental Science and Health, Part A, 2021
Zohre Javaheri Safa, Arta Olya, Mohammadreza Zamani, Mostafa Motalebi, Rahimeh Khalili, Kamahldin Haghbeen, Saeed Aminzadeh
The amount of cyanide consumed (M) can be measured by the amount of ammonia released in the reaction (M). In the presence of L-glutamate dehydrogenase (GDH), Ammonia reacts with alpha-ketoglutaric acid (KGA) and reduced nicotinamide adenine dinucleotide phosphate (NADPH) to generate L-glutamate and oxidized nicotinamide adenine dinucleotide phosphate (NADP+), as follows at Equation 5: