Glycolytic Reactions Research Articles

Expression levels and activity of rat liver lactate dehydrogenase isoenzymes in alloxan diabetes

A significant decrease in the activity of lactate dehydrogenase (LDH, EC 1.1.1.27) in liver cells of rats with alloxan diabetes was found due to a decrease in the expression of the corresponding genes. The decrease in the activity of the enzyme under study in experimental type I diabetes was associated with inactivation of the cytoplasmic isoform of LDH. It was found that the level of ldha and ldhb gene transcripts in the liver of healthy rats was higher than in animals with alloxan diabetes. The ldha gene expression demonstrated almost 9-fold decrease, while a decrease in the ldhb gene expression was less pronounced (just 1.25-fold). Probably, the decrease in the rate of functioning of the enzyme under study is associated with a decrease in the intensity of glucose uptake by cells, which leads to inhibition of glycolysis and intensification of all stages of gluconeogenesis, particularly, reversed glycolysis reactions. Thus, the data obtained by us indicate an important role of LDH in the adaptive response of cellular metabolism in the development of type I diabetes mellitus.

Expression levels and activity of rat liver lactate dehydrogenase isoenzymes in alloxan diabetes

A significant decrease in the activity of lactate dehydrogenase (LDH, EC 1.1.1.27) in liver cells of rats with alloxan diabetes was found due to a decrease in the expression of the corresponding genes. The decrease in the activity of the enzyme under study in experimental type I diabetes was associated with inactivation of the cytoplasmic isoform of LDH. It was found that the level of ldha and ldhb gene transcripts in the liver of healthy rats was higher than in animals with alloxan diabetes. The ldha gene expression demonstrated almost 9-fold decrease, while a decrease in the ldhb gene expression was less pronounced (just 1.25-fold). Probably, the decrease in the rate of functioning of the enzyme under study is associated with a decrease in the intensity of glucose uptake by cells, which leads to inhibition of glycolysis and intensification of all stages of gluconeogenesis, particularly, reversed glycolysis reactions. Thus, the data obtained by us indicate an important role of LDH in the adaptive response of cellular metabolism in the development of type I diabetes mellitus.V pecheni krys s alloksanovym diabetom obnaruzheno znachitel'noe snizhenie aktivnosti laktatdegidrogenazy (LDG, KF 1.1.1.27), obuslovlennoe umen'sheniem ékspressii sootvetstvuiushchikh genov. Éto snizhenie aktivnosti LDG, po-vidimomu, sviazano s umen'sheniem urovnia tsitoplazmaticheskoĭ izoformy LDG. Vyiavleno, chto kontsentratsiia transkriptov genov ldha i ldhb v pecheni zdorovykh krys vyshe, chem u zhivotnykh s alloksanovym diabetom. Prichem ékspressiia gena ldha byla snizhena pochti v 9 raz, togda kak ékspressiia gena ldhb snizhalas' vsego lish' v 1,25 raza. Poluchennye nami dannye svidetel'stvuiut o vazhnoĭ roli LDG v adaptivnoĭ reaktsii kletochnogo metabolizma pri razvitii sakharnogo diabeta I tipa.

Cinnamic acid derivative reduces tumor growth by decreasing Hif-1α expression and suppressing the Warburg effect

Background. Tumor growth is characterized by the presence of specific features that can be the basis for rational treatment. One of these features is the Warburg paradox, which manifests itself in the prevalence of glycolytic oxidation reactions over aerobic metabolism at adequate intracellular oxygen concentrations. Purpose. Under experimental conditions, to evaluate the possibility of correcting metabolic glycolytic abnormalities of tumor cells through course therapy with 4-hydroxy-3,5-di-tretbutyl cinnamic acid. Materials and methods. The study was performed on male Wistar rats, in which tumor cells of the C6-BU-1 line were implanted in the brain. The test compound 4-hydroxy3,5-di-tret butyl cinnamic acid and reference resveratrol were administered per os at doses of 100 mg/kg and 20 mg/kg, respectively, for 14 days from the moment of tumor inoculation. After the specified time, the rats were decapitated, the tumor tissue was extracted. In the course of the work, the volume of the tumor, the activity of ana/aerobic reactions of cellular metabolism, changes in mitochondrial biogenesis and the concentration of Hif-1a were determined. Results. The study showed that the course administration of resveratrol and 4-hydroxy3,5-di-tret butyl cinnamic acid contributed to a decrease in tumor volume compared to untreated animals by 22.9 % (p < 0.05) and 34.3 % (p < 0.05), respectively. Also, against the background of the use of the studied compound, there was a decrease in the content of Hif-1a by 27.4 % (p < 0.05), respectively, an increase in the activity of the enzymatic markers of mitochondrial biogenesis – succinate dehydrogenase and cytochrome-c oxidase by 166.7 % (p < 0.05) and 125.0 % (p < 0.05). The intensity of anaerobic metabolic reactions in rats treated by the test compound and resveratrol was significantly lower than in untreated rats, while the activity of aerobic processes considerably increased. Conclusion. The study showed that the administration of 4-hydroxy-3,5-di-tret butyl cinnamic acid reduces the intensity of anaerobic metabolism in tumor cells by reducing the expression of Hif-1a, which in turn suppresses tumor growth.

THE EFFECTIVENESS OF HIGH INTENSITY INTERVAL TRAINING WITH BLOOD FLOW RESTRICTION TRAINING ON ANAEROBIC THRESHOLD IN RUNNERS

The performance of runners is related to the anaerobic threshold level. Anaerobic threshold plays an important role in runner’s endurance. Anaerobic threshold value is also closely related to the level of runner’s fatigue when doing physical exercise or when competing for a long time. If the body’s endurance level cannot withstand the activities carried out, it will give a negative effect on their performance. There are exercises that aim to increase the anaerobic threshold value, namely high intensity interval training and blood flow restriction training. High intensity interval training can increase the anaerobic value through the mechanism of provide a high stimulus to anaerobic glycolytic and carbonic anhydrase reaction with formation (H+) that improved buffering capacity. Addition of blood flood restriction training by using limb occlusion pressure causes local hypoxia, so it will increase muscle metabolic demand. It will induce metabolic acidosis with increased hydrogen ions and lactate production.
 Key Words: High Intesity Interval Training; Blood Flow Restriction; Anaerobic Threshold; Anaerobic Capacity; Runners

Kallistatin/ serpina3c inhibits fibrosis after myocardial infarction by regulating glycolytic pathway

Abstract Background Fibrotic remodeling is the main pathological mechanism of heart failure after infarction. Studies have shown that the serine protease inhibitor Kallistatin/Serpina3c could inhibit the progression of myocardial hypertrophy and fibrosis after myocardial infarction, but the specific mechanism is unknown. Methods and results We used Serpina3c−/− and C57BL/6 mice to construct a MI model in vivo. TGF-β and hypoxia interfered with cardiac fibroblasts (CFs) to construct a fibrosis model in vitro. RNA-seq assessed the effect of Serpina3c knockout on the transcriptome. CCK-8 and BrdU were used to assess cell proliferation. Western blot and qPCR were used to verify the changes of glycolytic enzymes in the sequencing results. Co-IP was used to verify the interaction between Serpina3c and NR4A1. The results showed that Serpina3c expression decreased in the fibrotic tissue of MI heart and in the fibrosis model in vitro. After Serpina3c knockout, the degree of myocardial infarction fibrosis aggravated, and the proliferation and differentiation of CFs increased. Up-regulation of Serpina3c expression in CFs had the opposite effect, suggesting that Serpina3c had the ability to resist myocardial fibrosis. RNA-Seq results showed that glycolysis-related genes were significantly increased after Serpina3c knockout. Among them, the key enzyme of glycolysis, enolase (ENO1), had the largest change, and at the same time, the glycolysis reaction was enhanced. Inhibition of ENO1 can antagonize the promotion of Serpina3c knockout on the proliferation and differentiation of CFs. Activating the activity of NR4A1 could negatively regulate the expression of ENO1 and then inhibited the proliferation and differentiation of CFs. Conclusions Serpina3c inhibited the transcriptional activation of ENO1 by binding to NR4A1, and then reduced the fibrosis after myocardial infarction by inhibiting glycolysis. In short, Serpina3c provides a potential intervention target for the prevention and treatment of heart failure after infarction. Funding Acknowledgement Type of funding sources: Foundation. Main funding source(s): National Nature Science Foundation of China (No. 81770452) Serpina3c is a key protein in MI.

Chemical Recycling of PET in the Presence of the Bio-Based Polymers, PLA, PHB and PEF: A Review

The great increase in the production and consumption of plastics has resulted in large amounts of plastic wastes, creating a serious problem in terms of their environmentally friendly disposal. The need for the production of more environmentally friendly polymers gave birth to the production of biodegradable, and more recently, biobased polymers, used in the production of biodegradable or biobased plastics. Although the percentage of currently produced bioplastics is rather small, almost 1% compared to petrochemical-based plastics, inevitably is going to significantly increase in the near future due to strict legislation recently posed by the European Union and other countries’ Governments. Thus, recycling strategies that have been developed could be disturbed and the economic balance of this sector could be destabilized. In the present review, the recycling of the polymer mainly used in food plastic packaging, i.e., poly(ethylene terephthalate), PET is examined together with its counterparts from the biobased polymers, i.e., poly(lactic acid), PLA (already replacing PET in several applications), poly(3-hydroxybutyrate), PHB and poly(ethylene furanoate), PEF. Methods for the chemical recycling of these materials together with the chemical products obtained are critically reviewed. Specifically, hydrolysis, alcoholysis and glycolysis. Hydrolysis (i.e., the reaction with water) under different environments (alkaline, acidic, neutral), experimental conditions and catalysts results directly in the production of the corresponding monomers, which however, should be separated in order to be re-used for the re-production of the respective polymer. Reaction conditions need to be optimized with a view to depolymerize only a specific polymer, while the others remain intact. Alcoholysis (i.e., the reaction with some alcohol, methanol or ethanol) results in methyl or ethyl esters or diesters that again could be used for the re-production of the specific polymer or as a source for producing other materials. Glycolysis (reaction with some glycol, such as ethylene, or diethylene glycol) is much studied for PET, whereas less studied for the biopolymers and seems to be a very promising technique. Oligomers having two terminal hydroxyl groups are produced that can be further utilized as starting materials for other value-added products, such as unsaturated polyester resins, methacrylated crosslinked resins, biodegradable polyurethanes, etc. These diols derived from both PET and the bio-based polymers can be used simultaneously without the need for an additional separation step, in the synthesis of final products incorporating biodegradable units in their chemical structure.

Wnt signaling promotes tumor development in part through phosphofructokinase 1 platelet isoform upregulation.

The activation of Wnt signaling has been detected in various types of human cancer and has been shown to be associated with cancer development. In the present study, it was revealed that Wnt signaling induced the expression of phosphofructokinase 1 platelet isoform (PFKP), which has been reported to catalyze a rate‑limiting reaction in glycolysis and is important for the Warburg effect, proliferation, colony formation and cancer cell migration. Moreover, it was demonstrated that Wnt3A induced PFKP expression in a β‑catenin‑independent manner, resulting in increased PFK enzyme activity. Wnt3A‑induced epidermal growth factor receptor transactivation activated PI3K/AKT, which stabilized PFKP through PFKP S386 phosphorylation and subsequent PFKP upregulation. Wnt3A‑induced PFKP S386 phosphorylation increased PFKP expression and promoted the Warburg effect, cell proliferation, colony formation and the migratory ability of cancer cells. On the whole, the findings of the present study underscore the potential role of PFKP in Wnt signaling‑induced tumor development.

The Aerob and Anaerob Performance Beta-Alanine Supplement and Ergogenic Aid Using to the Power Output Variables in Cyclists: A Cohort Studies Random Model Effect

Supplement the use of ergogenic aids in cyclist’s directly have been improved the body metabolism and hemodynamic factors that are micro supplement in chancing reactions on the body muscle mass and limb muscle. Mostly knowing that, muscle power development progressive fast glycolytic and short time oxidative systems reactions. Sport competition intervals, therefore, during periods has been used specific drinks supported to cyclists. But, be obtained during should be long race times. Athletes directly needed some drug and fluid intake to prevent from metabolic breakdown rapidly the dynamic physiologic performance factors. Beta-alanine supplementation can be direct muscle performance development affects the anaerobic metabolism and capacity. It should be determined how the cyclists will use the competitive and training period intervals can increase the cyclists specific sprint and endurance race performance. Science cyclist International Road doses will be created in which, intervals can randomly effectively investigate. This study random cohort study is examined the effects of beta-alanine supplementation on aerobic and anaerobic power output in specific cyclists. Therefore, we have been databases PubMed, Scopus, and Medline initial search 10 August 2020 were created prospective effect the quality of bias work concluded Effect Size (ES) 95% Confidence Interval (CI) were used in the participant. Participants (N=66) have an age range of 25 to 38 of the using beta-alanine in training periods to endurance muscle performance, aerobic power, anaerobic power, and sprint time trials. As a result of beta-alanine improved anaerobic and aerobic power output on 4-week time-dependent trial performance condition. Significant values are obtained level factor-alpha <0.05 and p-value analysis pre-post interactive standardization.

Chemo‐enzymatic depolymerization of industrial and assorted post‐consumer poly(ethylene terephthalate) (PET) wastes using a eutectic‐based catalyst

AbstractBACKGROUNDEvery minute, 1 million bottled drinks were purchased worldwide in 2017. Poly(ethylene terephthalate) (PET) bottles are highly recalcitrant wastes, taking at least 450 years to decompose naturally, and their accumulation in the environment triggers a series of environmental impacts. Recycling is an environmentally friendly alternative to PET waste management. A two‐step PET depolymerization approach was studied in this work, comprising chemical glycolysis followed by enzymatic hydrolysis.RESULTSIn the glycolysis reaction, 100% PET was depolymerized in the presence of a eutectic solvent‐based catalyst and ethylene glycol, releasing bis(2‐hydroxyethyl) terephthalate (BHET) as the main product (70% yield). The recovered BHET was then hydrolysed by the highly efficient Candida antarctica lipase B, releasing terephthalic acid (TPA), achieving 0.98 of mole fraction in the best result of the experimental design. The overall yield of chemo‐enzymatic depolymerization of PET into TPA was 57%.CONCLUSIONUsing this integrated approach, a high overall yield of TPA from PET could be achieved within a short process timeframe (24 h). © 2021 Society of Chemical Industry (SCI).

Cobalt-based ionic liquid grafted on graphene as a heterogeneous catalyst for poly (ethylene terephthalate) glycolysis

Cobalt-based ionic liquid grafted on graphene surface (rGO\\[TESPMI]2CoCl4) was synthesized as a catalyst for glycolysis of polyethylene terephthalate (PET) and characterized by FTIR, XPS, Raman spectroscopy, XRD, TGA, FESEM, and EDS. This results disclosed that the chemical grafting was successfully performed. The high activity in mild condition and the simple recoverable from the reaction are the suitable characteristics of this catalyst. These aforementioned properties can be figured out with the PET conversion (100%) and yield (95.22%) of bis (hydroxyethyl terephthalate) (BHET) under optimal conditions. These results are owed to the synergistic effect between graphene and ionic liquid. Finally, the catalyst sustained activity for five cycles of reaction. To the best of our knowledge, prior to this research, ionic liquid grafted on a graphene surface had never been reported for the glycolysis reaction of PET. The green approach in this article, we proposed a recoverable and effective catalyst, which can be replaced with traditional catalysts that leave contaminants in the product.

Carbon flux around leaf-cytosolic glyceraldehyde-3-phosphate dehydrogenase introduces a 13C signal in plant glucose.

Within the plant and Earth sciences, stable isotope analysis is a versatile tool conveying information (inter alia) about plant physiological and paleoclimate variability across scales. Here, we identify a 13C signal (i.e. systematic 13C/12C variation) at tree-ring glucose C-4 and report an experimentally testable theory on its origin. We propose the signal is introduced by glyceraldehyde-3-phosphate dehydrogenases in the cytosol of leaves. It conveys two kinds of (potentially convoluted) information: (i) commitment of glyceraldehyde 3-phosphate to 3-phosphoglycerate versus fructose 1,6-bisphosphate metabolism; and (ii) the contribution of non-phosphorylating versus phosphorylating glyceraldehyde-3-phosphate dehydrogenase to catalysing the glyceraldehyde 3-phosphate to 3-phosphoglycerate forward reaction of glycolysis. The theory is supported by 13C fractionation modelling. Modelling results provide the first evidence in support of the cytosolic oxidation-reduction (COR) cycle, a carbon-neutral mechanism supplying NADPH at the expense of ATP and NADH, which may help to maintain leaf-cytosolic redox balances. In line with expectations related to COR cycling, we found a positive correlation between air vapour pressure deficit and 13C discrimination at glucose C-4. Overall, 13C-4 signal analysis may enable an improved understanding of leaf carbon and energy metabolism.

Transcriptomes of an oceanic diatom reveal the initial and final stages of acclimation to copper deficiency.

Copper (Cu) concentration is greatly reduced in the open sea so that phytoplankton must adjust their uptake systems and acclimate to sustain growth. Acclimation to low Cu involves changes to the photosynthetic apparatus and specific biochemical reactions that use Cu, but little is known how Cu affects cellular metabolic networks. Here we report results of whole transcriptome analysis of a plastocyanin-containing diatom, Thalassiosira oceanica 1005, during its initial stages of acclimation and after long-term adaptation in Cu-deficient seawater. Gene expression profiles, used to identify Cu-regulated metabolic pathways, show downregulation of anabolic and energy-yielding reactions in Cu-limited cells. These include the light reactions of photosynthesis, carbon fixation, nitrogen assimilation and glycolysis. Reduction of these pathways is consistent with reduced growth requirements for C and N caused by slower rates of photosynthetic electron transport. Upregulation of oxidative stress defence systems persists in adapted cells, suggesting cellular damage by increased reactive oxygen species (ROS) occurs even after acclimation. Copper deficiency also alters fatty acid metabolism, possibly in response to an increase in lipid peroxidation and membrane damage driven by ROS. During the initial stages of Cu-limitation the majority of differentially regulated genes are associated with photosynthetic metabolism, highlighting the chloroplast as the primary target of low Cu availability. The results provide insights into the mechanisms of acclimation and adaptation of T. oceanica to Cu deficiency.

Transcriptional Regulation of Plant Biomass Degradation and Carbohydrate Utilization Genes in the Extreme Thermophile Caldicellulosiruptor bescii.

ABSTRACTExtremely thermophilic bacteria from the genus Caldicellulosiruptor can degrade polysaccharide components of plant cell walls and subsequently utilize the constituting mono- and oligosaccharides. Through metabolic engineering, ethanol and other industrially important end products can be produced. Previous experimental studies identified a variety of carbohydrate-active enzymes in model species Caldicellulosiruptor saccharolyticus and Caldicellulosiruptor bescii, while prior transcriptomic experiments identified their putative carbohydrate uptake transporters. We investigated the mechanisms of transcriptional regulation of carbohydrate utilization genes using a comparative genomics approach applied to 14 Caldicellulosiruptor species. The reconstruction of carbohydrate utilization regulatory network includes the predicted binding sites for 34 mostly local regulators and point to the regulatory mechanisms controlling expression of genes involved in degradation of plant biomass. The Rex and CggR regulons control the central glycolytic and primary redox reactions. The identified transcription factor binding sites and regulons were validated with transcriptomic and transcription start site experimental data for C. bescii grown on cellulose, cellobiose, glucose, xylan, and xylose. The XylR and XynR regulons control xylan-induced transcriptional response of genes involved in degradation of xylan and xylose utilization. The reconstructed regulons informed the carbohydrate utilization reconstruction analysis and improved functional annotations of 51 transporters and 11 catabolic enzymes. Using gene deletion, we confirmed that the shared ATPase component MsmK is essential for growth on oligo- and polysaccharides but not for the utilization of monosaccharides. By elucidating the carbohydrate utilization framework in C. bescii, strategies for metabolic engineering can be pursued to optimize yields of bio-based fuels and chemicals from lignocellulose.IMPORTANCE To develop functional metabolic engineering platforms for nonmodel microorganisms, a comprehensive understanding of the physiological and metabolic characteristics is critical. Caldicellulosiruptor bescii and other species in this genus have untapped potential for conversion of unpretreated plant biomass into industrial fuels and chemicals. The highly interactive and complex machinery used by C. bescii to acquire and process complex carbohydrates contained in lignocellulose was elucidated here to complement related efforts to develop a metabolic engineering platform with this bacterium. Guided by the findings here, a clearer picture of how C. bescii natively drives carbohydrate utilization is provided and strategies to engineer this bacterium for optimal conversion of lignocellulose to commercial products emerge.

Metabonomic approaches investigate diosbulbin B-induced pulmonary toxicity and elucidate its underling mechanism in male mice.

Air Potato Yam is widely used in the treatment of many conditions such as cancer, inflammation, and goiter. Diosbulbin B (DIOB) is the primary active component of Air Potato Yam, and it exhibits anti-tumor and anti-inflammatory properties. The main purpose of this study was to determine the mechanism by which DIOB induces lung toxicity, using metabonomics and molecular biology techniques. The results showed that the lung toxicity induced by DIOB may occur because of a DIOB-induced increase in the plasma levels of long-chain free fatty acids and endogenous metabolites related to inflammation. In addition, treatment with DIOB increases the expression of the cyp3a13 enzyme, which leads to enhanced toxicity in a dose-dependent manner. The molecular mechanism underlying toxicity in mouse lung cells is the DIOB-mediated inhibition of fatty acid β-oxidation, partial glycolysis, and the TCA cycle, but DIOB treatment can also compensate for the low Adenosine triphosphate (ATP) supply levels by improving the efficiency of the last step of the glycolysis reaction and by increasing the rate of anaerobic glycolysis. Using metabonomics and other methods, we identified the toxic effects of DIOB on the lung and clarified the underlying molecular mechanism.

New thermodynamic activity-based approach allows predicting the feasibility of glycolysis

Thermodynamic feasibility analyses help evaluating the feasibility of metabolic pathways. This is an important information used to develop new biotechnological processes and to understand metabolic processes in cells. However, literature standard data are uncertain for most biochemical reactions yielding wrong statements concerning their feasibility. In this article we present activity-based equilibrium constants for all the ten glycolytic reactions, accompanied by the standard reaction data (standard Gibbs energy of reaction and standard enthalpy of reaction). We further developed a thermodynamic activity-based approach that allows to correctly determine the feasibility of glycolysis under different chosen conditions. The results show for the first time that the feasibility of glycolysis can be explained by thermodynamics only if (1) correct standard data are used and if (2) the conditions in the cell at non-equilibrium states are accounted for in the analyses. The results here will help to determine the feasibility of other metabolisms and to understand metabolic processes in cells in the future.

MultiTFA: a Python package for multi-variate thermodynamics-based flux analysis.

MotivationWe achieve a significant improvement in thermodynamic-based flux analysis (TFA) by introducing multivariate treatment of thermodynamic variables and leveraging component contribution, the state-of-the-art implementation of the group contribution methodology. Overall, the method greatly reduces the uncertainty of thermodynamic variables.ResultsWe present multiTFA, a Python implementation of our framework. We evaluated our application using the core Escherichia coli model and achieved a median reduction of 6.8 kJ/mol in reaction Gibbs free energy ranges, while three out of 12 reactions in glycolysis changed from reversible to irreversible.Availability and implementationOur framework along with documentation is available on https://github.com/biosustain/multitfa.Supplementary informationSupplementary data are available at Bioinformatics online.

Phosphodianion Activation of Enzymes for Catalysis of Central Metabolic Reactions.

The activation barriers ΔG⧧ for kcat/Km for the reactions of whole substrates catalyzed by 6-phosphogluconate dehydrogenase, glucose 6-phosphate dehydrogenase, and glucose 6-phosphate isomerase are reduced by 11–13 kcal/mol by interactions between the protein and the substrate phosphodianion. Between 4 and 6 kcal/mol of this dianion binding energy is expressed at the transition state for phosphite dianion activation of the respective enzyme-catalyzed reactions of truncated substrates d-xylonate or d-xylose. These and earlier results from studies on β-phosphoglucomutase, triosephosphate isomerase, and glycerol 3-phosphate dehydrogenase define a cluster of six enzymes that catalyze reactions in glycolysis or of glycolytic intermediates, and which utilize substrate dianion binding energy for enzyme activation. Dianion-driven conformational changes, which convert flexible open proteins to tight protein cages for the phosphorylated substrate, have been thoroughly documented for five of these six enzymes. The clustering of metabolic enzymes which couple phosphodianion-driven conformational changes to enzyme activation suggests that this catalytic motif has been widely propagated in the proteome.

Polyurethane resin derived from polyol of palm olein and recycled poly(ethylene terephthalate)

PurposePoly(ethylene terephthalate) (PET) waste from soft drink bottles was incorporated into palm olein alkyd to produce new polyol for use in polyurethane resins as surface protection on metal surfaces.Design/methodology/approachAlkyd was prepared from palm olein, glycerol and phthalic anhydride. PET underwent simultaneous glycolysis and transesterification reactions with the alkyd. Varying the amount of PET has led to polyols with different viscosities. Polyurethane resins were produced by reacting the polyols with toluene diisocyanate. The resins were coated on mild steel panels and cured. Performances of the cured films were tested.FindingsThe polyurethanes (PU) resin cured to a harder film with better thermal stability. Films showed excellent adhesion properties, while higher content of PET exhibited higher pencil hardness, better water, salt, acid and alkali resistance.Research limitations/implicationsOther vegetable oils could also be used. The alkyd structure could be changed by formulation to have different functionality and the ability to incorporate higher amount of PET waste. Rate of glycolysis of PET could be increased by higher amount of ethylene glycol.Practical implicationsThis method has managed to use waste PET in producing new polyol and PU resins. The cured films exhibit good mechanical and chemical properties, as well as excellent adhesion and thermal stability.Social implicationsThe non-biodegradable PET has created environmental pollution problems connected to littering and illegal landfilling. It has become necessary to pay greater attention to recycling PET bottles for obtaining valuable products.Originality/valueThis approach is different from the earlier reports, where PET was recycled to recover the raw materials.

Expression of the ace operon in Escherichia coli is triggered in response to growth rate-dependent flux-signal of ATP.

The signal that triggers the expression of the ace operon and, in turn, the transition of central metabolism's architecture from acetogenic to gluconeogenic in Escherichia coli remains elusive despite extensive research both in vivo and in vitro. Here, with the aid of flux analysis together with measurements of the enzymic activity of isocitrate lyase (ICL) and its aceA-messenger ribonucleuc acid (mRNA) transcripts, we provide credible evidence suggesting that the expression of the ace operon in E. coli is triggered in response to growth rate-dependent threshold flux-signal of adenosine triphosphate (ATP). Flux analysis revealed that the shortfall in ATP supply observed as the growth rate ($\mu $) diminishes from µmax to≤0.43h-1 ($ \pm 0.02;n4)\ $is partially redressed by up-regulating flux through succinyl CoA synthetase. Unlike glycerol and glucose, pyruvate cannot feed directly into the two glycolytic ATP-generating reactions catalyzed by phosphoglycerokinase and pyruvate kinase. On the other hand, glycerol, which upon its conversion to D-glyceraldehyde, feeds into the phosphorylation and dephosphorylation parts of glycolysis including the substrate-level phosphorylation-ATP generating reactions, thus preventing ATP flux from dropping to the critical threshold signal required to trigger the acetate-diauxic switch until glycerol is fully consumed. The mRNA transcriptional patterns of key gluconeogenic enzymes, namely, ackA, acetate kinase; pta, phosphotransacetylase; acs, acetyl CoA synthetase and aceA, ICL, suggest that the pyruvate phenotype is better equipped than the glycerol phenotype for the switch from acetogenic to gluconeogenic metabolism.

Glycolysis: an efficient route for recycling of end of life polyurethane foams

The increased applications of Polyurethane (PU) materials give rise to a higher amount of wastes, which have a devastating effect on the earth in turn; therefore, the management of end-of-life wastes is one of the most important issues in the modern world. Although incineration and landfilling are the most common procedure adopted for waste disposal, but both of them caused environmental problems such as air and soil pollution. Moreover, the former triggers global warming, and the latter causes water pollution making the problem worst. As a consequence, finding economical and environmentally friendly methods are a high priority topic for researchers to overcome this problem. Fortunately, recycling is an environmentally attractive solution, and there is an increased interest by the researchers in recycling PU wastes. Several recycling techniques for PUs have been described in the technical and scientific literature. Without any doubt, glycolysis reaction is one of the most important recycling method, especially for rigid and flexible PUs. In this review, glycolysis of waste polyurethane foam (PUF) materials with different glycols and catalysts, especially metallic ones were considered, and the effect of some additional parameters such as the nature of glycol, catalyst, temperature and material ratio were discussed too. In addition, a brief description on characterization of recycled products, and potential application of regenerated products is carried out.