scholarly journals Enzymatic evolution driven by entropy production

2018 ◽  
Author(s):  
A. Arango-Restrepo ◽  
J.M. Rubi ◽  
D. Barragán
Keyword(s):  
Enzyme Kinetics ◽  
Entropy Production ◽  
Intermediate State ◽  
State Energy ◽  
Structural Evolution ◽  
Thermodynamic Efficiency ◽  
Total Entropy ◽  
Enzymatic Process ◽  
Intermediate States ◽  
Evolution Proceeds

AbstractWe show that the structural evolution of enzymes is largely influenced by the entropy produced in the enzymatic process. We have computed this quantity for the case in which the process has unstable and metastable intermediate states. By assuming that the kinetics takes place along a potential barrier, we have found that the behavior of the total entropy produced is a non-monotonic function of the intermediate state energy. By diminishing the number of metastable intermediate states, the total entropy produced decreases and consequently the enzyme kinetics and the thermodynamic efficiency are enhanced. Minimizing locally the total entropy produced for an enzymatic process with metastable intermediate states, the kinetics and the thermodynamic efficiency are raised. In contrast, in the absence of metastable intermediate states, a maximum of the entropy produced results in an improvement of the kinetic performance although the thermodynamic efficiency diminishes. Our results show that the enzymatic evolution proceeds not only to enhance the kinetics but also to optimize the total entropy produced.

scholarly journals Entropy and Entropy Production in Multiscale Dynamics

2019 ◽  
Vol 44 (3) ◽  
pp. 217-233 ◽  
Author(s):  
Miroslav Grmela ◽  
Michal Pavelka ◽  
Václav Klika ◽  
Bing-Yang Cao ◽  
Nie Bendian
Keyword(s):  
Heat Conduction ◽  
Entropy Production ◽  
Total Entropy ◽  
Approach To Equilibrium ◽  
Multiscale Dynamics ◽  
Classical Thermodynamics ◽  
Point Of Departure ◽  
Total Entropy Production ◽  
Classical Entropy

Abstract Heat conduction is investigated on three levels: equilibrium, Fourier, and Cattaneo. The Fourier level is either the point of departure for investigating the approach to equilibrium or the final stage in the investigation of the approach from the Cattaneo level. Both investigations bring to the Fourier level an entropy and a thermodynamics. In the absence of external and internal influences preventing the approach to equilibrium the entropy that arises in the latter investigation is the production of the classical entropy that arises in the former investigation. If the approach to equilibrium is prevented, then the entropy that arises in the investigation of the approach from the Cattaneo level to the Fourier level still brings to the Fourier level the entropy and the thermodynamics even if the classical entropy and the classical thermodynamics are absent. We also note that vanishing total entropy production as a characterization of equilibrium state is insufficient.

scholarly journals Maximum Entropy Production Theorem for Transitions between Enzyme Functional States and Its Applications

Entropy ◽  
2019 ◽  
Vol 21 (8) ◽  
pp. 743 ◽  
Author(s):  
Davor Juretić ◽  
Juraj Simunić ◽  
Željana Bonačić Lošić
Keyword(s):  
Free Energy ◽  
Entropy Production ◽  
Conformational Changes ◽  
Triosephosphate Isomerase ◽  
Biological Evolution ◽  
Maximal Entropy ◽  
Total Entropy ◽  
Functional States ◽  
Rate Limiting ◽  
Total Entropy Production

Transitions between enzyme functional states are often connected to conformational changes involving electron or proton transport and directional movements of a group of atoms. These microscopic fluxes, resulting in entropy production, are driven by non-equilibrium concentrations of substrates and products. Maximal entropy production exists for any chosen transition, but such a maximal transitional entropy production (MTEP) requirement does not ensure an increase of total entropy production, nor an increase in catalytic performance. We examine when total entropy production increases, together with an increase in the performance of an enzyme or bioenergetic system. The applications of the MTEP theorem for transitions between functional states are described for the triosephosphate isomerase, ATP synthase, for β-lactamases, and for the photochemical cycle of bacteriorhodopsin. The rate-limiting steps can be easily identified as those which are the most efficient in dissipating free-energy gradients and in performing catalysis. The last step in the catalytic cycle is usually associated with the highest free-energy dissipation involving proton nanocurents. This recovery rate-limiting step can be optimized for higher efficiency by using corresponding MTEP requirements. We conclude that biological evolution, leading to increased optimal catalytic efficiency, also accelerated the thermodynamic evolution, the synergistic relationship we named the evolution-coupling hypothesis.

scholarly journals Effects of non-uniform nanoparticle concentration on entropy generation

2021 ◽  
Vol 68 (1 Jan-Feb) ◽  
Author(s):  
Ahmer Mehmood ◽  
Sajid Khan ◽  
Muhammad Usman
Keyword(s):  
Entropy Production ◽  
Entropy Generation ◽  
Working Fluid ◽  
Physical Parameters ◽  
Bejan Number ◽  
Total Entropy ◽  
Entropy Generation Number ◽  
Self Similar Solution ◽  
Nanoparticles Concentration ◽  
The Impact

The entropy generation analysis of a thermal process is capable of determining the efficiency of that process and is therefore helpful to optimize the thermal system operating under various conditions. There are several ingredients upon which the phenomenon of entropy generation can depend, such as the nature of flow and the fluid, the assumed conditions, and the material properties of the working fluid. However, the dependence of entropy generation phenomenon upon such properties has so far not been fully realized, in view of the existing literature. On the other hand, based upon the existing studies, it has been established that the non-uniform concentration of nanoparticles in the base fluid does cause to enhance the heat transfer rate. Therefore, it is logical to investigate the entropy production under the impact of non-homogenous distribution of nanoparticles. Based upon this fact the aim of current study is to explore a comprehensive detail about the influence of non-homogeneous nanoparticles concentration on entropy production phenomenon by considering a laminar viscous flow past a moving continuous flat plate. Non-uniform concentration is considered in the nanofluid modeling in which the Brownian and thermophoretic diffusions are considered which impart significant effects on velocity and temperature profiles. An exact self-similar solution to this problem is observed to be possible and is reported. The effects of various controlling physical parameters such as Brinkman number, Schmidt number, Prandtl number, diffusion parameter, and concentration parameter on both local as well as total entropy generation number and Bejan number are elaborated by several graphs and Tables. The obtained results reveal a significant impact of all aforementioned parameters on entropy generation characteristics. It is observed that by a 20% increase in nanoparticles concentration the total entropy generation is increased up to 67% for a set of fixed values of remaining parameters.

scholarly journals Biophysical properties of intermediate states of EMT outperform both epithelial and mesenchymal states

2019 ◽  
Author(s):  
Yoran Margaron ◽  
Tomoaki Nagai ◽  
Laurent Guyon ◽  
Laetitia Kurzawa ◽  
Anne-Pierre Morel ◽  
...  
Keyword(s):  
Mechanical Properties ◽  
Tumor Cell ◽  
Intermediate State ◽  
Mesenchymal Cells ◽  
Primary Breast Tumor ◽  
Tumor Cell Dissemination ◽  
Intermediate States ◽  
Defined Culture ◽  
Contractile Forces ◽  
Cell Dissemination

AbstractPotential metastatic cells can dissociate from a primary breast tumor by undergoing an epithelial-to-mesenchymal transmission (EMT). Recent work has revealed that cells in intermediate states of EMT acquire an augmented capacity for tumor-cell dissemination. These states have been characterized by molecular markers, but the structural features and the cellular mechanisms that underlie the acquisition of their invasive properties are still unknown. Using human mammary epithelial cells, we generated cells in intermediate states of EMT through the induction of a single EMT-inducing transcription factor, ZEB1, and cells in a mesenchymal state by stimulation with TGFβ. In stereotypic and spatially-defined culture conditions, the architecture, internal organization and mechanical properties of cells in the epithelial, intermediate and mesenchymal state were measured and compared. We found that the lack of intercellular cohesiveness in epithelial and mesenchymal cells can be detected early by microtubule destabilization and the repositioning of the centrosome from the cell-cell junction to the cell center. Consistent with their high migration velocities, cells in intermediate states produced low contractile forces compared with epithelial and mesenchymal cells. The high contractile forces in mesenchymal cells powered a retrograde flow pushing the nucleus away from cell adhesion to the extracellular matrix. Therefore, cells in intermediate state had structural and mechanical properties that were distinct but not necessarily intermediate between epithelial and mesenchymal cells. Based on these observations, we found that a panel of triple-negative breast cancer lines had intermediate rather than mesenchymal characteristics suggesting that the structural and mechanical properties of the intermediate state are important for understanding tumor-cell dissemination.

Superconductors in Alternating Magnetic Fields

1937 ◽  
Vol 33 (4) ◽  
pp. 559-576 ◽  
Author(s):  
D. Shoenberg
Keyword(s):  
Intermediate State ◽  
Royal Society ◽  
State Energy ◽  
Time Lag ◽  
Energy Losses ◽  
Anisotropic Structure ◽  
Superconducting Sphere ◽  
Induced Currents ◽  
The Difference ◽  
Alternating Magnetic Fields

A method of studying magnetic properties in alternating fields and its application to the intermediate state of a superconducting sphere are described. It is shown that the behaviour of the sphere in alternating fields of frequencies between 10 and 100 is different from that in very slowly varying fields, the difference becoming less for lower frequencies and for smaller radius. When the specimen is in the intermediate state, energy losses are produced in it by the alternating field, showing that the induced currents are out of phase with the alternating field. The induced currents do not, however, flow in the same way as in a homogeneous isotropic conductor, and this is probably on account of an anisotropic structure of the specimen when in the intermediate state. This structure depends strongly on the amplitude of the alternating field in such a way that the effective average conductivity is increased with decreasing amplitude, and this amplitude effect depends on the size of the specimen. Evidence is given for a time lag in the magnetocaloric effect, and this time lag decreases with decrease of the size of the specimen, being of order sec. for a sphere of about 1 cm. diameter.In conclusion I wish to thank Prof. Lord Rutherford and Dr Cockcroft for their interest in this work; Dr Peierls for suggesting the experiment and for much valuable advice and assistance; Mr Shire for advice on some technical points; and various members of the staff of the Royal Society Mond Laboratory for help in the measurements.

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