Similarities of modulation by temperature

Journal of Mathematical Chemistry, 2010

In this work, we study the qualitative properties of the model proposed by Selkov Eur J Biochem 4: 79-86 (1968) for the description of the glycolytic oscillations. First we show that the Selkov's model can be put in form of a Newton's equation, thus allowing to define a pseudo-energy. Then, we show without imposing additional conditions that the limit cycle, if it exists, it is unique and globally attractive, thus precluding the possibility of multi-rythmicity. Finally, based on energetic and geometric considerations, we investigate the global properties of the unique equilibrium (idest of the arrest of the oscillations). Some biochemical remarks on the relevance of the uniqueness of sustained oscillations end the work.

Journal of Theoretical Biology, 2008

Based on the distribution of activation energies around the experimental mean and averaging of rate constants we propose a theoretical scheme to examine the temperature dependence and temperature compensation of time periods of chemical oscillations. The critical finite width of the distribution is characteristic of endogeneous oscillations for compensating kinetics as observed in circadian oscillations, while the vanishing width corresponds to Arrhenius temperature dependent kinetics of non-endogeneous chemical oscillation in Belousov-Zhabotinskii reaction in a CSTR or glycolysis in cell-free yeast extracts. Our theoretical analysis is corroborated with experimental data.

International Journal of Molecular Sciences

For systems biology, it is important to describe the kinetic and thermodynamic properties of enzyme-catalyzed reactions and reaction cascades quantitatively under conditions prevailing in the cytoplasm. While in part I kinetic models based on irreversible thermodynamics were tested, here in part II, the influence of the presumably most important cytosolic factors was investigated using two glycolytic reactions (i.e., the phosphoglucose isomerase reaction (PGI) with a uni-uni-mechanism and the enolase reaction with an uni-bi-mechanism) as examples. Crowding by macromolecules was simulated using polyethylene glycol (PEG) and bovine serum albumin (BSA). The reactions were monitored calorimetrically and the equilibrium concentrations were evaluated using the equation of state ePC-SAFT. The pH and the crowding agents had the greatest influence on the reaction enthalpy change. Two kinetic models based on irreversible thermodynamics (i.e., single parameter flux-force and two-parameter Noor...

This commentary is on the concept used by Ding and Luo (2013) to measure the rate of entropy production in normal cell and cancerous cell lines under an alternating electric field. The authors placed the 96-well plate containing the cells (incubated for 60 min in an incubator at 37 C) in the electric field for 300 s and recorded the change of temperature of cells and culture medium T F (t) (t ¼ 0–300 s) with a transducer. The control group was placed in the same apparatus without electric field, and the change of temperature T C (t), was also recorded. The heat transfer rates of _ Q C and _ Q F without and with alternating electric fields (AEFs), respectively, from the cell to outward are calculated from Fourier's law of heat conduction. The contribution of heat transfer from the medium was obtained and subtracted to determine the net heat transfer with or without (AEFs) from the cell only. The entropy change of a cell with or without AEFs is expressed by the entropy balance:

Bioelectrochemistry and Bioenergetics, 1991

Febs Journal, 2005

This work concerns the cause of glycolytic oscillations in yeast. We analyse experimental data as well as models in two distinct cases: the relaxation-like oscillations seen in yeast extracts, and the sinusoidal Hopf oscillations seen in intact yeast cells. In the case of yeast extracts, we use flux-change plots and model analyses to establish that the oscillations are driven by on/off switching of phosphofructokinase. In the case of intact yeast cells, we find that the instability leading to the appearance of oscillations is caused by the stoichiometry of the ATP-ADP-AMP system and the allosteric regulation of phosphofructokinase, whereas frequency control is distributed over the reaction network. Notably, the NAD+/NADH ratio modulates the frequency of the oscillations without affecting the instability. This is important for understanding the mutual synchronization of oscillations in the individual yeast cells, as synchronization is believed to occur via acetaldehyde, which in turn affects the frequency of oscillations by changing this ratio.

Innovative Food Science & Emerging Technologies, 2018

The aim of this work was to evaluate differences in energy flows between normal and immortalized cells when these distinct biological systems are exposed to environmental stimulation. These differences were considered using a constructal thermodynamic approach, and were subsequently verified experimentally. The application of constructal law to cell analysis led to the conclusion that temperature differences between cells with distinct behaviour can be amplified by interaction between cells and external fields. Experimental validation of the principle was carried out on two cellular models exposed to electromagnetic fields. By infrared thermography we were able to assess small changes in heat dissipation measured as a variation in cell internal energy. The experimental data thus obtained are in agreement with the theoretical calculation, because they show a different thermal dispersion pattern when normal and immortalized cells are exposed to electromagnetic fields. By using two methods that support and validate each other, we have demonstrated that the cell/environment interaction can be exploited to enhance cell behavior differences, in particular heat dissipation. We propose infrared thermography as a technique effective in discriminating distinct patterns of thermal dispersion and therefore able to distinguish a normal phenotype from a transformed one. One of the fundamental abilities of the human body is its temperature control and regulation, which has been crucial for survival throughout human history 1–3. A temperature variation of more than 3.5 °C from the mean resting body temperature of 37 °C could be fatal; indeed, for temperatures above 42 °C both the cellular cytoskeleton and organ and central nervous system function can be damaged 4. Different strategies are involved in regulating body temperature and in maintaining physiological homeostasis; humans regulate their body temperature through a balance of heat production, absorption and loss 1,5. A temperature difference is required between cells and their environment, in order for them to survive 6. For example, the related temperature gradient has been evaluated as approximately 0.4 °C cm −1 for Streptococcus faecalis 7. This temperature difference is the driving force of the heat flows between cells and their environment across the membrane.

Advances in Enzyme Regulation, 1981

International Journal of Molecular Sciences, 2020

In systems biology, material balances, kinetic models, and thermodynamic boundary conditions are increasingly used for metabolic network analysis. It is remarkable that the reversibility of enzyme-catalyzed reactions and the influence of cytosolic conditions are often neglected in kinetic models. In fact, enzyme-catalyzed reactions in numerous metabolic pathways such as in glycolysis are often reversible, i.e., they only proceed until an equilibrium state is reached and not until the substrate is completely consumed. Here, we propose the use of irreversible thermodynamics to describe the kinetic approximation to the equilibrium state in a consistent way with very few adjustable parameters. Using a flux-force approach allowed describing the influence of cytosolic conditions on the kinetics by only one single parameter. The approach was applied to reaction steps 2 and 9 of glycolysis (i.e., the phosphoglucose isomerase reaction from glucose 6-phosphate to fructose 6-phosphate and the enolase-catalyzed reaction from 2-phosphoglycerate to phosphoenolpyruvate and water). The temperature dependence of the kinetic parameter fulfills the Arrhenius relation and the derived activation energies are plausible. All the data obtained in this work were measured efficiently and accurately by means of isothermal titration calorimetry (ITC). The combination of calorimetric monitoring with simple flux-force relations has the potential for adequate consideration of cytosolic conditions in a simple manner.