Search results for "glycolysi"

Kinetic modelling of the Zymomonas mobilis Entner-Doudoroff pathway: insights into control and functionality.

2013

Zymomonas mobilis, an ethanol-producing bacterium, possesses the Entner-Doudoroff (E-D) pathway, pyruvate decarboxylase and two alcohol dehydrogenase isoenzymes for the fermentative production of ethanol and carbon dioxide from glucose. Using available kinetic parameters, we have developed a kinetic model that incorporates the enzymic reactions of the E-D pathway, both alcohol dehydrogenases, transport reactions and reactions related to ATP metabolism. After optimizing the reaction parameters within likely physiological limits, the resulting kinetic model was capable of simulating glycolysis in vivo and in cell-free extracts with good agreement with the fluxes and steady-state intermediate …

Metabolic Profiling of Glucose-Fed Metabolically Active Resting Zymomonas mobilis Strains

2020

Zymomonas mobilis is the most efficient bacterial ethanol producer and its physiology is potentially applicable to industrial-scale bioethanol production. However, compared to other industrially important microorganisms, the Z. mobilis metabolome and adaptation to various nutritional and genetic perturbations have been poorly characterized. For rational metabolic engineering, it is essential to understand how central metabolism and intracellular redox balance are maintained in Z. mobilis under various conditions. In this study, we applied quantitative mass spectrometry-based metabolomics to explore how glucose-fed non-growing Z. mobilis Zm6 cells metabolically adapt to change of oxygen avai…

Biostimulant Potential of Humic Acids Extracted From an Amendment Obtained via Combination of Olive Mill Wastewaters (OMW) and a Pre-treated Organic …

2018

Olive mill wastewaters (OMW) detain contain significant levels of phenolic compounds with antimicrobial/phytotoxic activity and high amounts of undecomposed organic matter that may a high pollutant load that exerts negative effects on soil biology because of significant levels in phenolic compounds with antimicrobial/phytotoxic activity and limited biodegradability, and high amounts of undecomposed organic matter. Among OMW detoxification techniques, those focusing on oxidative degradation of phenolic compounds are relevant those focusing on oxidative degradation of phenolic compounds to reduce their toxicity. The composting (bio-oxidation) process in particular, exploits exothermic oxidati…

Fructose 2,6-bisphosphate as a signal for changing from sugar to lipid oxidation during flight in locusts

1986

AbstractFlight in locusts is initially powered mainly by carbohydrate but if flight is to be sustained, as in migration, the animals have to utilize fat as the predominant fuel. The molecular basis of this metabolic switch has not been identified. Fructose 2,6-bisphosphate is a potent activator of 6-phosphofructokinase (EC 2.7.1.11) purified from locust flight muscle. After the first few minutes of flight in the locust the concentration of fructose 2,6-bisphosphate in the flight muscle falls dramatically, which should lead to a decrease in the activity of 6-phosphofructokinase as part of the mechanism to conserve carbohydrate during prolonged flight.

Hypoxia-Induced Extracellular Acidosis Increases p-Glycoprotein Activity and Chemoresistance in Tumors in Vivo via p38 Signaling Pathway

2011

Due to inadequate perfusion, tumors develop hypoxia and extracellular acidosis. In vitro, this acidic environment (pH=6.6) has a strong impact on the acitvity of the p-glycoprotein (pGP) drug transporter responsible for multidrug resistance. This effect is most probably mediated via p38 and/or ERK1/2 signalling pathways. The aimof the studywas to analyzewhether these findings also play a role for chemosensitivity in solid growing tumors in vivo. Therefore, experimental R3327-AT1 tumors of the rat were exposed to an acidifying treatment leading to forced glycolysis. The intratumoral pO21 was determined polarographically and the extracellular pH was measured with needle electrodes. In additio…

Exercise and the Control of Glycolysis in Vertebrate Muscle: The Effects of Intensive Work, Fatigue and Recovery on Muscle Metabolites and Effectors …

1994

Properties of locust muscle 6-phosphofructokinase and their importance in the regulation of glycolytic flux during prolonged flight

1987

6-Phosphofructokinase (PFK, EC 2.7.1.11) from the flight muscle of the locust (Locusta migratoria) was purified to a specific activity of 80 μmol min−1 (mg protein)−1 (at 25°C). 1. The enzyme is made up from subunits ofMr-81600, and the smallest catalytically active form is likely to be a tetramer. 2. PFK activity is markedly affected by the pH of the assay; the optimum pH was at about 8. 3. Physiological concentrations of ATP strongly inhibit locust PFK by shifting the S0.5 for fructose 6-phosphate (concentration required for 50% of maximum activity) out of the physiological concentration range. At pH 7.4 and about physiological concentrations of ATP, the curve of PFK activity against the …

Metabolic Escape Routes of Cancer Stem Cells and Therapeutic Opportunities

2020

Although improvement in early diagnosis and treatment ameliorated life expectancy of cancer patients, metastatic disease still lacks effective therapeutic approaches. Resistance to anticancer therapies stems from the refractoriness of a subpopulation of cancer cells—termed cancer stem cells (CSCs)—which is endowed with tumor initiation and metastasis formation potential. CSCs are heterogeneous and diverge by phenotypic, functional and metabolic perspectives. Intrinsic as well as extrinsic stimuli dictated by the tumor microenvironment (TME)have critical roles in determining cell metabolic reprogramming from glycolytic toward an oxidative phenotype and vice versa, allowing cancer cells to th…

Relationships between metabolic fluxes and enzyme amino acid composition

2013

AbstractMetabolic fluxes are a key parameter of metabolic pathways being closely related to the kinetic properties of enzymes and could be conditional on their sequence characteristics. This study examines possible relationships between the metabolic fluxes and the amino acid (AA) composition (AAC) for enzymes from the yeast Saccharomyces cerevisiae glycolysis pathway. Metabolic fluxes were quantified by the COPASI tool using the kinetic models of Hynne and Teusink at 25 mM, 50 mM, and 100 mM of external glucose or employing literature data for cognate kinetic or stoichiometric models. The enzyme sequences were taken from the UniProtKB, and the AAC computed by the ExPASy/ProtParam tool. Mul…

Amino acid-based cholinium ionic liquids as sustainable catalysts for pet depolymerization

2021

Chemical recycling to monomers is one of the key strategies in tackling the issues deriving from persistent plastic pollution in the environment, and poly(ethylene terephthalate) (PET) is among the most used polymers in modern society. In this context, we herein describe the glycolysis of PET to bis-hydroxyethyl terephthalate (BHET), promoted by basic cholinium salts differing for the anions, also comprising amino acid anions. We investigated the optimal reaction conditions, finding that the best-performing catalyst is [Ch][Gly], in the presence of which a conversion of 85% and a yield of 51% are achieved at 150 °C after 6 h, from PET deriving from a clear water bottle. We used our protocol…