A new model with internal variables for theoretical thermodynamic characterization of hemoglobin: Entropy determination and comparative study

Thermodynamics Characterization of Lung Carcinoma, Entropic Study and Metabolic Correlations

In recent years, the use of dielectric spectroscopy as an investigation technique to determine the chemical–physical characteristics of biological materials has had a great increase. This study used the non-equilibrium thermodynamics with internal variables theory to test the potential pathological features of lung cancer. After a brief exploration of the dielectric polarization concept highlighting some aspects that were used, some thermodynamic functions were obtained as functions of the frequency, both for lung tumor cells and physiological ones. Variations in the intensity of values but not in the trend of the curves were observed and this was attributed to the perturbing field. The trend of this field explains the behavior of phenomena described by other functions, as related to the frequencies of the perturbing field. Compared to the physiological ones, the cancer cells appeared to be “more predisposed” to conserve their state as characterized by minor entropy production, probably because this helped cells to obtain the required adenosine triphosphate (ATP) from the minimum amount of nutrients.

A New Model for Thermodynamic Characterization of Hemoglobin

In this paper, we formulate a thermodynamic model of hemoglobin that describes, by a physical point of view, phenomena favoring the binding of oxygen to the protein. Our study is based on theoretical methods extrapolated by experimental data. After some remarks on the non-equilibrium thermodynamic theory with internal variables, some thermodynamic functions are determined by the value of the complex dielectric constant. In previous papers, we determined the explicit expression of a dielectric constant as a function of a complex dielectric modulus and frequency. The knowledge of these functions allows a new characterization of the material and leads to the study of new phenomena that has yet to be studied. In detail, we introduce the concept of “hemoglobe”, a model that considers the hemoglobin molecule as a plane capacitor, the dielectric of which is almost entirely constituted by the quaternary structure of the protein. This model is suggested by considering a phenomenological coefficient of the non-equilibrium thermodynamic theory related to the displacement polarization current. The comparison of the capacity determined by the mean of this coefficient, and determined by geometrical considerations, gives similar results; although more thermodynamic information is derived by the capacity determined considering the aforementioned coefficient. This was applied to the normal human hemoglobin, homozygous sickle hemoglobin, and sickle cell hemoglobin C disease. Moreover, the energy of the capacitor of the three hemoglobin was determined. Through the identification of displacement currents, the introduction of this model presents new perspectives and helps to explain hemoglobin functionality through a physical point of view.