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Andrew Iverson, Erin Garza, Ryan Manow, Jinhua Wang, Yuanyuan Gao, Scott Grayburn, Shengde Zhou
BACKGROUND: Anaerobic rather than aerobic fermentation is preferred for conversion of biomass derived sugars to high value redox-neutral and reduced commodities. This will likely result in a higher yield of substrate to product conversion and decrease production cost since substrate often accounts for a significant portion of the overall cost. To this goal, metabolic pathway engineering has been used to optimize substrate carbon flow to target products. This approach works well for the production of redox neutral products such as lactic acid from redox neutral sugars using the reducing power NADH (nicotinamide adenine dinucleotide, reduced) generated from glycolysis (2 NADH per glucose equivalent)...
2016: BMC Systems Biology
E Mariotti, M R Orton, O Eerbeek, J F Ashruf, C J Zuurbier, R Southworth, T R Eykyn
Hyperpolarized (13)C MR measurements have the potential to display non-linear kinetics. We have developed an approach to describe possible non-first-order kinetics of hyperpolarized [1-(13)C] pyruvate employing a system of differential equations that agrees with the principle of conservation of mass of the hyperpolarized signal. Simultaneous fitting to a second-order model for conversion of [1-(13)C] pyruvate to bicarbonate, lactate and alanine was well described in the isolated rat heart perfused with Krebs buffer containing glucose as sole energy substrate, or glucose supplemented with pyruvate...
April 2016: NMR in Biomedicine
Mohammed Ali Azam, Cory S Wagg, Stéphane Massé, Talha Farid, Patrick F H Lai, Marjan Kusha, John Asta, Rafael Jaimes, Sarah Kuzmiak-Glancy, Matthew W Kay, Gary D Lopaschuk, Kumaraswamy Nanthakumar
Ventricular fibrillation (VF) is an important cause of sudden cardiac arrest following myocardial infarction. Following resuscitation from VF, decreased cardiac contractile function is a common problem. During and following myocardial ischemia, decreased glucose oxidation, increased anaerobic glycolysis for cardiac energy production are harmful and energetically expensive. The objective of the present study is to determine the effects of dichloroacetate (DCA), a glucose oxidation stimulator, on cardiac contractile dysfunction following ischemia-induced VF...
November 2015: American Journal of Physiology. Heart and Circulatory Physiology
Sara Rodríguez-Enríquez, Luz Hernández-Esquivel, Alvaro Marín-Hernández, Mohammed El Hafidi, Juan Carlos Gallardo-Pérez, Ileana Hernández-Reséndiz, José S Rodríguez-Zavala, Silvia C Pacheco-Velázquez, Rafael Moreno-Sánchez
Oxidative phosphorylation (OxPhos) is functional and sustains tumor proliferation in several cancer cell types. To establish whether mitochondrial β-oxidation of free fatty acids (FFAs) contributes to cancer OxPhos functioning, its protein contents and enzyme activities, as well as respiratory rates and electrical membrane potential (ΔΨm) driven by FFA oxidation were assessed in rat AS-30D hepatoma and liver (RLM) mitochondria. Higher protein contents (1.4-3 times) of β-oxidation (CPT1, SCAD) as well as proteins and enzyme activities (1...
August 2015: International Journal of Biochemistry & Cell Biology
Daniele Gabriel-Costa, Telma Fatima da Cunha, Luiz Roberto Grassmann Bechara, Rodrigo Soares Fortunato, Luiz Henrique Marchesi Bozi, Marcele de Almeida Coelho, Maria Luiza Barreto-Chaves, Patricia Chakur Brum
BACKGROUND: Besides its role as a fuel source in intermediary metabolism, lactate has been considered a signaling molecule modulating lactate-sensitive genes involved in the regulation of skeletal muscle metabolism. Even though the flux of lactate is significantly high in the heart, its role on regulation of cardiac genes regulating lactate oxidation has not been clarified yet. We tested the hypothesis that lactate would increase cardiac levels of reactive oxygen species and up-regulate the expression of genes related to lactate oxidation complex...
2015: PloS One
Vitalba Ruggieri, Francesca Agriesti, Rosella Scrima, Ilaria Laurenzana, Donatella Perrone, Tiziana Tataranni, Carmela Mazzoccoli, Lorenzo Lo Muzio, Nazzareno Capitanio, Claudia Piccoli
Reprogramming of metabolism is a well-established property of cancer cells that is receiving growing attention as potential therapeutic target. Oral squamous cell carcinomas (OSCC) are aggressive and drugs-resistant human tumours displaying wide metabolic heterogeneity depending on their malignant genotype and stage of development. Dichloroacetate (DCA) is a specific inhibitor of the PDH-regulator PDK proved to foster mitochondrial oxidation of pyruvate. In this study we tested comparatively the effects of DCA on three different OSCC-derived cell lines, HSC-2, HSC-3, PE15...
January 20, 2015: Oncotarget
Philip Hasel, Sean Mckay, Jing Qiu, Giles E Hardingham
Neurodegenerative and neurological disorders are often characterised by pathological changes to dendrites, in advance of neuronal death. Oxidative stress, energy deficits and excitotoxicity are implicated in many such disorders, suggesting a potential vulnerability of dendrites to these situations. Here we have studied dendritic vs. somatic responses of primary cortical neurons to these types of challenges in real-time. Using a genetically encoded indicator of intracellular redox potential (Grx1-roGFP2) we found that, compared to the soma, dendritic regions exhibited more dramatic fluctuations in redox potential in response to sub-lethal ROS exposure, and existed in a basally more oxidised state...
September 2015: Biochimica et Biophysica Acta
Michael A Moxley, Daniel A Beard, Jason N Bazil
Dihydrolipoamide dehydrogenase is a flavoenzyme that reversibly catalyzes the oxidation of reduced lipoyl substrates with the reduction of NAD(+) to NADH. In vivo, the dihydrolipoamide dehydrogenase component (E3) is associated with the pyruvate, α-ketoglutarate, and glycine dehydrogenase complexes. The pyruvate dehydrogenase (PDH) complex connects the glycolytic flux to the tricarboxylic acid cycle and is central to the regulation of primary metabolism. Regulation of PDH via regulation of the E3 component by the NAD(+)/NADH ratio represents one of the important physiological control mechanisms of PDH activity...
December 16, 2014: Biophysical Journal
Fatemah A Hermes, John E Cronan
The lipoate coenzyme is essential for function of the pyruvate (PDH) and 2-oxoglutarate (OGDH) dehydrogenases and thus for aerobic growth of Escherichia coli. LipB catalyzes the first step in lipoate synthesis, transfer of an octanoyl moiety from the fatty acid synthetic intermediate, octanoyl-ACP, to PDH and OGDH. E. coli also encodes LplA, a ligase that in presence of exogenous octanoate (or lipoate) can bypass loss of LipB. LplA imparts ΔlipB strains with a 'leaky' growth phenotype on aerobic glucose minimal medium supplemented with succinate (which bypasses the OGDH-catalyzed reaction), because it scavenges an endogenous octanoate pool to activate PDH...
October 10, 2014: Molecular Microbiology
Casey L Quinlan, Renata L S Goncalves, Martin Hey-Mogensen, Nagendra Yadava, Victoria I Bunik, Martin D Brand
Several flavin-dependent enzymes of the mitochondrial matrix utilize NAD(+) or NADH at about the same operating redox potential as the NADH/NAD(+) pool and comprise the NADH/NAD(+) isopotential enzyme group. Complex I (specifically the flavin, site IF) is often regarded as the major source of matrix superoxide/H2O2 production at this redox potential. However, the 2-oxoglutarate dehydrogenase (OGDH), branched-chain 2-oxoacid dehydrogenase (BCKDH), and pyruvate dehydrogenase (PDH) complexes are also capable of considerable superoxide/H2O2 production...
March 21, 2014: Journal of Biological Chemistry
Yuki Doi, Motoyuki Shimizu, Tomoya Fujita, Akira Nakamura, Noboru Takizawa, Naoki Takaya
We identified the extremely nitrite-tolerant bacterium Achromobacter denitrificans YD35 that can grow in complex medium containing 100 mM nitrite (NO2(-)) under aerobic conditions. Nitrite induced global proteomic changes and upregulated tricarboxylate (TCA) cycle enzymes as well as antioxidant proteins in YD35. Transposon mutagenesis generated NO2(-)-hypersensitive mutants of YD35 that had mutations at genes for aconitate hydratase and α-ketoglutarate dehydrogenase in the TCA cycle and a pyruvate dehydrogenase (Pdh) E1 component, indicating the importance of TCA cycle metabolism to NO2(-) tolerance...
March 2014: Applied and Environmental Microbiology
Carlotta Debnar-Daumler, Andreas Seubert, Georg Schmitt, Johann Heider
Anaerobic phenylalanine metabolism in the denitrifying betaproteobacterium Aromatoleum aromaticum is initiated by conversion of phenylalanine to phenylacetate, which is further metabolized via benzoyl-coenzyme A (CoA). The formation of phenylacetate is catalyzed by phenylalanine transaminase, phenylpyruvate decarboxylase, and a phenylacetaldehyde-oxidizing enzyme. The presence of these enzymes was detected in extracts of cells grown with phenylalanine and nitrate. We found that two distinct enzymes are involved in the oxidation of phenylacetaldehyde to phenylacetate, an aldehyde:ferredoxin oxidoreductase (AOR) and a phenylacetaldehyde dehydrogenase (PDH)...
January 2014: Journal of Bacteriology
Jae Hyung Lim, Sang Woo Seo, Se Yeon Kim, Gyoo Yeol Jung
The intracellular redox state plays an important role in the cellular physiology that determines the efficiency of chemical and biofuel production by microbial cell factories. However, it is difficult to achieve optimal redox rebalancing of synthetic pathways owing to the sensitive responses of cellular physiology according as the intracellular redox state changes. Here, we demonstrate optimal rebalancing of the intracellular redox state by model-driven control of expression using n-butanol production in Escherichia coli as a model system...
November 2013: Metabolic Engineering
Enxuan Jing, Brian T O'Neill, Matthew J Rardin, André Kleinridders, Olga R Ilkeyeva, Siegfried Ussar, James R Bain, Kevin Y Lee, Eric M Verdin, Christopher B Newgard, Bradford W Gibson, C Ronald Kahn
Sirt3 is an NAD(+)-dependent deacetylase that regulates mitochondrial function by targeting metabolic enzymes and proteins. In fasting mice, Sirt3 expression is decreased in skeletal muscle resulting in increased mitochondrial protein acetylation. Deletion of Sirt3 led to impaired glucose oxidation in muscle, which was associated with decreased pyruvate dehydrogenase (PDH) activity, accumulation of pyruvate and lactate metabolites, and an inability of insulin to suppress fatty acid oxidation. Antibody-based acetyl-peptide enrichment and mass spectrometry of mitochondrial lysates from WT and Sirt3 KO skeletal muscle revealed that a major target of Sirt3 deacetylation is the E1α subunit of PDH (PDH E1α)...
October 2013: Diabetes
Guifang Chang, Zhenglin Luo, Sitian Gu, Qinghang Wu, Ming Chang, Xingguo Wang
DHA production by Schizochytrium sp. S31 was studied in batch cultures on glycerol with stepwise dissolved oxygen strategy. Three growth stages were identified as cell growth, lipid accumulation and lipid turnover. It was revealed that fatty acid (FA) shifts during the three growth stages involved the activity changes of glycerol kinase (GK), FAD(+)-dependent glycerol-3-phosphate dehydrogenase (FAD(+)-G-3-PDH), malic enzyme (ME), ATP citrate lyase (ACL) and NAD(+)-dependent isocitrate dehydrogenase (NAD(+)-ICDH)...
August 2013: Bioresource Technology
John R Ussher, Jagdip S Jaswal, Gary D Lopaschuk
The pyridine nucleotides NAD(+) and NADP(+) play a pivotal role in regulating intermediary metabolism in the heart. The intracellular NAD(+)/NADH ratio controls flux through various dehydrogenase enzymes involved in both anaerobic and aerobic metabolism and also regulates posttranslational protein modification. The intracellular NADP(+)/NADPH ratio controls flux through the pentose phosphate pathway (PPP) and the polyol pathway, while also regulating ion channel function and oxidative stress. Not only does the NAD(+)/NADH ratio regulate the rates of ATP production, it can also modify energy substrate preference...
August 17, 2012: Circulation Research
H Wulf, H Mallin, U T Bornscheuer
The polyol dehydrogenase PDH-11300 from Deinococcus geothermalis was cloned, functionally expressed in Escherichia coli and biochemically characterized. The enzyme showed the highest activity in the oxidation of xylitol and 1,2-hexanediol and had an optimum temperature of 45 °C. The enzyme exhibited a T⁶⁰₅₀-value of 48.3 °C. The T⁶⁰₅₀ is the temperature where 50% of the initial activity remains after incubation for 1h. In order to elucidate the structural reasons contributing to thermostability, the substrate-binding loop of PDH-11300 was substituted by the loop-region of a homolog enzyme, the galactitol dehydrogenase from Rhodobacter sphaeroides (PDH-158), resulting in a chimeric enzyme (PDH-loop)...
September 10, 2012: Enzyme and Microbial Technology
Federica Valsecchi, Claire Monge, Marleen Forkink, Ad J C de Groof, Giovanni Benard, Rodrigue Rossignol, Herman G Swarts, Sjenet E van Emst-de Vries, Richard J Rodenburg, Maria A Calvaruso, Leo G J Nijtmans, Bavo Heeman, Peggy Roestenberg, Be Wieringa, Jan A M Smeitink, Werner J H Koopman, Peter H G M Willems
Human mitochondrial complex I (CI) deficiency is associated with progressive neurological disorders. To better understand the CI pathomechanism, we here studied how deletion of the CI gene NDUFS4 affects cell metabolism. To this end we compared immortalized mouse embryonic fibroblasts (MEFs) derived from wildtype (wt) and whole-body NDUFS4 knockout (KO) mice. Mitochondria from KO cells lacked the NDUFS4 protein and mitoplasts displayed virtually no CI activity, moderately reduced CII, CIII and CIV activities and normal citrate synthase and CV (F(o)F(1)-ATPase) activity...
October 2012: Biochimica et Biophysica Acta
Akira Ota, Akira Nakashima, Yoko S Kaneko, Keiji Mori, Hiroshi Nagasaki, Takeshi Takayanagi, Mitsuyasu Itoh, Kazunao Kondo, Toshiharu Nagatsu, Miyuki Ota
Aripiprazole is the only atypical antipsychotic drug known to cause the phosphorylation of AMP-activated protein kinase (AMPK) in PC12 cells. However, the molecular mechanisms underlying this phosphorylation in aripiprazole-treated PC12 cells have not yet been clarified. Here, using PC12 cells, we show that these cells incubated for 24 h with aripiprazole at 50 μM and 25 mM glucose underwent a decrease in their NAD⁺/NADH ratio. Aripiprazole suppressed cytochrome c oxidase (COX) activity but enhanced the activities of pyruvate dehydrogenase (PDH), citrate synthase and Complex I...
November 2012: Journal of Neural Transmission
Zhentao Sun, Phi Minh Do, Mun Su Rhee, Lakshmanan Govindasamy, Qingzhao Wang, Lonnie O Ingram, K T Shanmugam
Pyruvate dehydrogenase (PDH) of Escherichia coli is inhibited by NADH. This inhibition is partially reversed by mutational alteration of the dihydrolipoamide dehydrogenase (LPD) component of the PDH complex (E354K or H322Y). Such a mutation in lpd led to a PDH complex that was functional in an anaerobic culture as seen by restoration of anaerobic growth of a pflB, ldhA double mutant of E. coli utilizing a PDH- and alcohol dehydrogenase-dependent homoethanol fermentation pathway. The glutamate at position 354 in LPD was systematically changed to all of the other natural amino acids to evaluate the physiological consequences...
May 2012: Microbiology
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