Biomedical subjects

G N Chuev

Publications and source records attributed to G N Chuev.

11 recordsLinked to original sources

PubMed2006

Hydration of hydrophobic solutes treated by the fundamental measure approach.

We have developed a method to calculate the hydration of hydrophobic solutes by the fundamental measure theory. This method allows us to carry out calculations of the density profile and the hydration energy for hydrophobic molecules. An additional benefit of the method is the possibility to calculate interaction forces between solvated nanoparticles. Based on the designed method, we calculate hydration of spherical solutes of various sizes from one angstrom up to several nanometers. We have applied methods to evaluate the free energies, the enthalpies, and the entropies of hydrated rare gases and hydrocarbons. The obtained results are in agreement with available experimental data and simulations.

Chemistry, Physical↗

PubMed2004

Wavelet treatment of the intrachain correlation functions of homopolymers in dilute solutions.

Discrete wavelets are applied to the parametrization of the intrachain two-point correlation functions of homopolymers in dilute solutions obtained from Monte Carlo simulations. Several orthogonal and biorthogonal basis sets have been investigated for use in the truncated wavelet approximation. The quality of the approximation has been assessed by calculation of the scaling exponents obtained from the des Cloizeaux ansatz for the correlation functions of homopolymers with different connectivities in a good solvent. The resulting exponents are in better agreement with those from recent renormalization group calculations as compared to the data without the wavelet denoising. We also discuss how the wavelet treatment improves the quality of data for correlation functions from simulations of homopolymers at varied solvent conditions and of heteropolymers.

Journal Article↗

PubMed2004

Wavelet treatment of structure and thermodynamics of simple liquids.

A new algorithm is developed to solve integral equations for simple liquids. The algorithm is based on the discrete wavelet transform of radial distribution functions. The Coifman 2 basis set is employed for the wavelet treatment. To solve integral equations we have applied the combined scheme in which the coarse part of the solution is calculated by wavelets, while the fine part by the direct iterations. Tests on the PY and HNC approximations have indicated that the proposed procedure is more effective than the conventional method based on the hybrid algorithm. Possibilities for application of the method to molecular liquids and mixed quantum-classical systems are discussed.

Journal Article↗

PubMed2003

Wavelet treatment of radial distribution functions of solutes.

Discrete wavelets are applied to parametrize the radial distribution functions of hydrated ions and hydrophobic solutes. The data on radial distribution functions are derived from the integral equation theory and neutron scattering experiment. The Coifman and the discrete Meyer basis sets are used for the wavelet approximation. The quality of the approximation is verified by calculations of the solvation energy, the coordination number, and the change in chemical potential of solutes.

Journal Article↗

PubMed2001

Mean-field treatment of polarons in strong electrolytes.

Using variational estimates for the grand partition function, we have developed a microscopic theory of an excess electron in an ionic liquid at high ion concentrations. We have derived the free-energy functional for the electron and have calculated electron energies for the ground and the first excited states as well as electron-ion correlation functions versus thermodynamic parameters of liquid and parameters of electron-ion potentials. We have found that the energetic characteristics of solvated electron are mainly determined by the Coulomb interaction which gives birth to polaronlike states, while ion cores have a pronounced quantitative effect on these characteristics. The local solvent structure around the excess electron is determined by the mean field induced by ions. Using the method developed we have calculated polaron characteristics in molten salts, such as the maximum of the absorption spectrum and its variations caused by changes in temperature, density, and composition of the electrolyte. The data obtained are in agreement with experiments and computer simulations.

Journal Article↗

PubMed1993

A polaron model for electron transfer in globular proteins.

Polaron models have been considered for the electron states in protein globules existing in a solvent. These models account for two fundamental effects, viz, polarization interaction of an electron with the conformational vibrations and the heterogeneity of the medium. Equations have been derived to determine the electron state in a protein globule. The parameters of this state show that it is an extended state with an energy of 2 eV. The electron transfer rate for cyt C self-exchange reaction has been calculated in the polaron model. Reorganization energy, tunneling matrix element and the rate constant have also been estimated. The results are compared with experimental data. The influence of model parameters on the significance of the data obtained has been studied. The potentialities of the model are discussed.

Electron Transport↗

PubMedDate not supplied

[Electron transfer between globular proteins. Evaluation of a matrix element].

The dependence of the matrix element of the probability of interprotein electron transfer on the mutual orientation of the donor and acceptor centers and the distance between them was calculated. The calculations were made under the assumption that electron transfer proceeds mainly by a collective excitation of polaron nature, like a solvated electron state. The results obtained are consistent with experimental data and indicate the nonexponential behavior of this dependence in the case when the distance transfer is less than 20 A.

Electron Transport↗

PubMedDate not supplied

[Electron transfer between globular proteins. Dependence of the rate of transfer on distance].

Based on the assumption that electron transfer between globular proteins occurs by a collective excitation of polaron type, the dependence of the rate of this process on the distance between the donor and acceptor centers with regard to their detailed electron structure was calculated. The electron structure of the heme was calculated by the quantum-chemical MNDO-PM3 method. The results were compared with experimental data on interprotein and intraglobular electron transfer. It is shown that, in the framework of this model, the electron transfer is not exponential and does not require a particular transfer pathway since the whole protein macromolecule is involved in the formation of the electron excited state.

Electron Transport↗

PubMedDate not supplied

[A probabilistic method for the calculation of energy of hydrophobic interactions].

A theoretical approach to the quantitative estimation of the energy of hydrophobic interactions on the molecular level has been developed. The model is based on the fundamental relationship between the probability of shaping of a cavity of the excluded volume in liquid water that results from fluctuations of density and free energy of prime hydrophobic solvates, hard spheres. This probability was estimated with the use of the probabilistic method in combination with experimentally observed data on density and radial distribution function of allocation. Free energy of hydrophobic interactions for a complex consisting of several hard spheres was determined. The critical value of the particles included in the complex was estimated.

Hydrophobic and Hydrophilic Interactions↗

PubMedDate not supplied

[Estimation of the hydrophobic effect based on the density functional theory].

Using the fundamental measure treatment of the density functional theory, we have developed a method to calculate the solvation of hydrophobic solutes. The method allows one to calculate the density profile and the solvation energy for hydrophobic molecules. An additional benefit of the method is the possibility to calculate interaction forces and the mean force potential between hydrophobic nanoparticles. On the basis of the method, the solvation energies for spherical solutes of different sizes from one angstrom up to several nanometers were calculated.

Algorithms↗

PubMedDate not supplied

[Long-range electron transfer in globular proteins by polaron excitation].

Considering polaron model, we have calculated an electron state localized in the protein heme. Using these calculations: the electron density and electron energy, we estimated the self-exchange rate constant for cyt c (horse heart), its reorganization energy, matrix element, and dependence of this rate on the distance between hemes. The results are compared with the experimental data and other theoretical estimations. We discuss the role of polaron excitations in the long-range electron transfer in globular proteins.

Electrons↗