scholarly journals Pyruvate:ferredoxin oxidoreductase and low abundant ferredoxins support aerobic photomixotrophic growth in cyanobacteria

2021 ◽  
Author(s):  
Yingying Wang ◽  
Xi Chen ◽  
Katharina Spengler ◽  
Karoline Terberger ◽  
Marko Boehm ◽  
...  
Keyword(s):  
Free Energy ◽  
Gibbs Free Energy ◽  
Thermodynamic Equilibrium ◽  
Pyruvate Dehydrogenase ◽  
Carbon Metabolism ◽  
Aerobic Conditions ◽  
Metabolic Reactions ◽  
Pyruvate:Ferredoxin Oxidoreductase ◽  
Central Reaction

The decarboxylation of pyruvate is a central reaction in the carbon metabolism of all organisms. Both the pyruvate:ferredoxin oxidoreductase (PFOR) and the pyruvate dehydrogenase (PDH) complex catalyze this reaction. Whereas PFOR reduces ferredoxin, the PDH complex utilizes NAD+. Anaerobes rely on PFOR, which was replaced during evolution by the PDH complex found in aerobes. Cyanobacteria possess both. Our data challenge the view that PFOR is exclusively utilized for fermentation. Instead, we show, that the cyanobacterial PFOR is stable in the presence of oxygen in vitro and is required for optimal photomixotrophic growth under aerobic conditions while the PDH complex is inactivated under the same conditions. We found that cells rely on a general shift from utilizing NAD(H)-dependent to ferredoxin-dependent enzymes under these conditions. The utilization of ferredoxins instead of NAD(H) saves a greater share of the Gibbs free energy, instead of wasting it as heat. This obviously simultaneously decelerates metabolic reactions as they operate closer to their thermodynamic equilibrium. It is common thought that during evolution, ferredoxins were replaced by NAD(P)H due to their higher stability in an oxidizing atmosphere. However, utilization of NAD(P)H could also have been favored due to a higher competitiveness because of an accelerated metabolism.

scholarly journals DOCKING KURKUMIN DAN SENYAWA ANALOGNYA PADA RESEPTOR PROGESTERON: STUDI INTERAKSINYA SEBAGAI Selective Progesterone Receptor Modulators (SPRMs)

2012 ◽  
Vol 13 (2) ◽  
pp. 55-60
Author(s):  
Edy Meiyanto
Keyword(s):  
Free Energy ◽  
Progesterone Receptor ◽  
Gibbs Free Energy ◽  
Curcuma Longa ◽  
Ocimum Basilicum ◽  
Receptor Modulators ◽  
Selective Progesterone Receptor Modulators ◽  
Progesterone Receptor Modulators

Kurkumin merupakan suatu kandungan dari Curcuma longa L.,yang telah dibuktikan efek sitotoksiknya secara in vitro terhadap sel kanker payudara. Senyawa analog kurkumin: PGV-0, PGV-1, HGV-0, dan HGV-1, hasil modifikasi dari kurkumin, diperkirakan memiliki aksi yang sama. Penelitian ini bertujuan untuk mengetahui afinitas dan interaksi dari kurkumin dan analognya sebagai Selective Progesterone Receptor Modulators (SPRMs) dalam mengadakan inhibisi kompetitif dengan hormon progesteron. Optimasi geometri struktur kurkumin dan analognya dilakukan dengan software Hyperchem 7.5. Konformasi optimum PGV-0 dan PGV-1 dihasilkan melalui metode AM1 sedangkan kurkumin, HGV-0, dan HGV-1 dengan metode PM3. Kemudian dilakukan proses docking senyawa uji dengan bindingsite hormon progesteron pada reseptor progesteron (IA28) menggunakan software Arguslab 4.01, dalam kondisi ada dan tanpa air. Proses ini dilakukan dengan metode GAdock. Dari proses docking diperoleh nilai (Gibbs free energy)DG terendah pada senyawa kurkumin bentuk keto baik dengan maupun tanpa air. Afinitas terbesar turunan kurkumin ditunjukkan oleh PGV-1 pada keadaan ada air dan  HGV-1 tanpa air pada reseptor progesteron. 'font-family: "Arial","sans-serif";mso-ansi-language:IN'Kata kunci: kurkumin dan analognya, SPRMs, docking, reseptor  progesteron IA28 -language:IN'Antiradikal, DPPH, IC50, fenolik total, Elephantopus schaber L., Ocimum basilicum L.forma citratum Back., Graptophylum pictum Griff, Gynura procumbens Merr. 

Chemical equilibrium and chemical kinetics

2018 ◽  
Author(s):  
Dennis Sherwood ◽  
Paul Dalby
Keyword(s):  
Free Energy ◽  
Equilibrium Constant ◽  
Gibbs Free Energy ◽  
Chemical Kinetics ◽  
Chemical Equilibrium ◽  
First Principles ◽  
Effect Of Temperature ◽  
Total System ◽  
Free Energies

Building on the previous chapter, this chapter examines gas phase chemical equilibrium, and the equilibrium constant. This chapter takes a rigorous, yet very clear, ‘first principles’ approach, expressing the total Gibbs free energy of a reaction mixture at any time as the sum of the instantaneous Gibbs free energies of each component, as expressed in terms of the extent-of-reaction. The equilibrium reaction mixture is then defined as the point at which the total system Gibbs free energy is a minimum, from which concepts such as the equilibrium constant emerge. The chapter also explores the temperature dependence of equilibrium, this being one example of Le Chatelier’s principle. Finally, the chapter links thermodynamics to chemical kinetics by showing how the equilibrium constant is the ratio of the forward and backward rate constants. We also introduce the Arrhenius equation, closing with a discussion of the overall effect of temperature on chemical equilibrium.

scholarly journals Genetic Perturbation of Pyruvate Dehydrogenase Kinase 1 Modulates Growth, Angiogenesis and Metabolic Pathways in Ovarian Cancer Xenografts

Cells ◽  
2021 ◽  
Vol 10 (2) ◽  
pp. 325
Author(s):  
Carolina Venturoli ◽  
Ilaria Piga ◽  
Matteo Curtarello ◽  
Martina Verza ◽  
Giovanni Esposito ◽  
...  
Keyword(s):  
Ovarian Cancer ◽  
Cancer Cells ◽  
Pyruvate Dehydrogenase ◽  
Metabolic Pathways ◽  
Negative Impact ◽  
Digital Pathology ◽  
Pyruvate Dehydrogenase Kinase ◽  
Ovarian Cancer Cells ◽  
Pyruvate Dehydrogenase Kinase 1

Pyruvate dehydrogenase kinase 1 (PDK1) blockade triggers are well characterized in vitro metabolic alterations in cancer cells, including reduced glycolysis and increased glucose oxidation. Here, by gene expression profiling and digital pathology-mediated quantification of in situ markers in tumors, we investigated effects of PDK1 silencing on growth, angiogenesis and metabolic features of tumor xenografts formed by highly glycolytic OC316 and OVCAR3 ovarian cancer cells. Notably, at variance with the moderate antiproliferative effects observed in vitro, we found a dramatic negative impact of PDK1 silencing on tumor growth. These findings were associated with reduced angiogenesis and increased necrosis in the OC316 and OVCAR3 tumor models, respectively. Analysis of viable tumor areas uncovered increased proliferation as well as increased apoptosis in PDK1-silenced OVCAR3 tumors. Moreover, RNA profiling disclosed increased glucose catabolic pathways—comprising both oxidative phosphorylation and glycolysis—in PDK1-silenced OVCAR3 tumors, in line with the high mitotic activity detected in the viable rim of these tumors. Altogether, our findings add new evidence in support of a link between tumor metabolism and angiogenesis and remark on the importance of investigating net effects of modulations of metabolic pathways in the context of the tumor microenvironment.

Extended Gibbs Free Energy and Laplace Pressure of Ordered Hexagonal Close-Packed Spherical Particles: A Wettability Study

Langmuir ◽  
2021 ◽  
Author(s):  
Amir Bayat ◽  
Mahdi Ebrahimi ◽  
Saeed Rahemi Ardekani ◽  
Esmaiel Saievar Iranizad ◽  
Alireza Zaker Moshfegh
Keyword(s):  
Free Energy ◽  
Gibbs Free Energy ◽  
Laplace Pressure ◽  
Spherical Particles ◽  
Hexagonal Close Packed

scholarly journals First-Principles Study of Mechanical and Thermodynamic Properties of Binary and Ternary CoX (X = W and Mo) Intermetallic Compounds

Materials ◽  
2021 ◽  
Vol 14 (6) ◽  
pp. 1404
Author(s):  
Yunfei Yang ◽  
Changhao Wang ◽  
Junhao Sun ◽  
Shilei Li ◽  
Wei Liu ◽  
...  
Keyword(s):  
Free Energy ◽  
Thermodynamic Properties ◽  
Gibbs Free Energy ◽  
Density Functional ◽  
Vibrational Entropy ◽  
Functional Theory ◽  
Lattice Constants ◽  
The Density Functional Theory ◽  
Ductile Behavior ◽  
Pseudo Potential

In this study, the structural, elastic, and thermodynamic properties of DO19 and L12 structured Co3X (X = W, Mo or both W and Mo) and μ structured Co7X6 were investigated using the density functional theory implemented in the pseudo-potential plane wave. The obtained lattice constants were observed to be in good agreement with the available experimental data. With respect to the calculated mechanical properties and Poisson’s ratio, the DO19-Co3X, L12-Co3X, and μ-Co7X6 compounds were noted to be mechanically stable and possessed an optimal ductile behavior; however, L12-Co3X exhibited higher strength and brittleness than DO19-Co3X. Moreover, the quasi-harmonic Debye–Grüneisen approach was confirmed to be valid in describing the temperature-dependent thermodynamic properties of the Co3X and Co7X6 compounds, including heat capacity, vibrational entropy, and Gibbs free energy. Based on the calculated Gibbs free energy of DO19-Co3X and L12-Co7X6, the phase transformation temperatures for DO19-Co3X to L12-Co7X6 were determined and obtained values were noted to match well with the experiment results.

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