12 research outputs found
Spectral properties of quasi-one-dimensional conductors with a finite transverse band dispersion
We determine the one-particle spectral function and the corresponding derived
quantities for the conducting chain lattice with the finite inter-chain hopping
and the three-dimensional long-range Coulomb electron-electron
interaction. The standard approximation is used. It is shown that,
due to the optical character of the anisotropic plasmon dispersion caused by
the finite , the low energy quasi-particle -peak appears in
the spectral function in addition to the hump present at the energies of the
order of plasmon energy. The particular attention is devoted to the continuous
cross-over from the non-Fermi liquid to the Fermi liquid regime by increasing
. It is shown that the spectral weight of the hump transfers to the
quasi-particle as the optical gap in the plasmon dispersion increases together
with , with the quasi-particle residuum behaving like in the limit . Our approach is appropriate for
the wide range of energy scales given by the plasmon energy and the width of
the conduction band, and is complementary to the Luttinger liquid techniques
that are limited to the low energy regime close to the Fermi surface
Maximum Entropy Production Theorem for Transitions between Enzyme Functional States and Its Applications
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
Muzički odgoj u našim odgojno-obrazovnim ustanovama
Rad ne sadrži sažetak
Muzički odgoj u našim odgojno-obrazovnim ustanovama
Rad ne sadrži sažetak
Theoretical Improvements in Enzyme Efficiency Associated with Noisy Rate Constants and Increased Dissipation
Previous studies have revealed the extraordinarily large catalytic efficiency of some enzymes. High catalytic proficiency is an essential accomplishment of biological evolution. Natural selection led to the increased turnover number, kcat, and enzyme efficiency, kcat/KM, of uni–uni enzymes, which convert a single substrate into a single product. We added or multiplied random noise with chosen rate constants to explore the correlation between dissipation and catalytic efficiency for ten enzymes: beta-galactosidase, glucose isomerase, β-lactamases from three bacterial strains, ketosteroid isomerase, triosephosphate isomerase, and carbonic anhydrase I, II, and T200H. Our results highlight the role of biological evolution in accelerating thermodynamic evolution. The catalytic performance of these enzymes is proportional to overall entropy production—the main parameter from irreversible thermodynamics. That parameter is also proportional to the evolutionary distance of β-lactamases PC1, RTEM, and Lac-1 when natural or artificial evolution produces the optimal or maximal possible catalytic efficiency. De novo enzyme design and attempts to speed up the rate-limiting catalytic steps may profit from the described connection between kinetics and thermodynamics
The maximum entropy production principle and linear irreversible processes
It is shown that Onsager’s principle of the least dissipation of energy is equivalent to the maximum entropy production principle. It is known that solutions of the linearized Boltzmann equation make extrema of entropy production. It is argued, in the case of stationary processes, that this extremum is a maximum rather than a minimum
The Maximum Entropy Production Principle and Linear Irreversible Processes
It is shown that Onsager’s principle of the least dissipation of energy is equivalent to the maximum entropy production principle. It is known that solutions of the linearized Boltzmann equation make extrema of entropy production. It is argued, in the case of stationary processes, that this extremum is a maximum rather than a minimum