The murburn precepts for aerobic respiration and redox homeostasis.

Murburn concept is a new perspective to metabolism which posits that certain redox enzymes/proteins mediate catalysis outside their active site, via diffusible reactive oxygen species (DROS, usually deemed as toxic wastes). We have recently questioned the proton-centric chemiosmotic rotary ATP synthesis (CRAS) explanation for mitochondrial oxidative phosphorylation (mOxPhos) and proposed an oxygen-centric murburn model in lieu. Herein, the chemical equations and thermodynamic foundations for this new model of mOxPhos are detailed. Standard transformed Gibbs free energy values of respiratory reactions are calculated to address the spontaneity, control, and efficiency of oxidative phosphorylation. Unlike the deterministic/multi-molecular and 'irreducibly complex' CRAS model, the stochastic/bimolecular and parsimonious murburn reactions afford a more viable precept for the variable and non-integral stoichiometry, higher yield for NADH than FADH2, and origin/evolution of oxygen-centric cellular life. Also, we present tangible DROS-based explanations for the multiple roles of various reaction components, HCN > H2S order of cellular toxicity in aerobes, and explain why oxygen inhibits anaerobes. We highlight the thermodynamic significance of proton deficiency in NADH/mitochondria and link the 'oxygen → DROS → water' metabolic pathway to the macroscopic physiologies of ATP-synthesis, trans-membrane potential, thermogenesis, and homeostasis. We also provide arguments for the extension of the murburn bioenergetics model to life under anoxic and extreme/unique habitats. In the context of mOxPhos, our findings imply that DROS should be seen as an essential requisite for life, and not merely as pathophysiological manifestations.

Standard Values of the Thermodynamic Functions of the Formation of Ions in an Aqueous Solution and their Change during Solvation.

The standard thermodynamic parameters of inorganic ions in an aqueous solution are based on the use of a convention on the zero values of the thermodynamic functions of protons. However, this does not allow calculating the thermodynamic parameters of reactions in which, along with ions, organic and inorganic compounds participate, the thermodynamic parameters of which are determined in the standard system of values since frames of reference are different. In this work, we calculated the standard thermodynamic parameters of inorganic ions in an aqueous solution in the same system of values that is used for organic compounds. The calculation of the standard values of the Gibbs function, enthalpy, and entropy is based on the use of reliably determined thermodynamic parameters of protons in an aqueous solution according to Tissandier et al. [ J. Phys. Chem. A, 1998, 102, 7787-7794]. The results allow one to calculate the thermodynamic parameters of reactions in aqueous media with the participation of inorganic ions and organic compounds. In this work, the thermodynamic parameters of solvation processes in aqueous solutions are determined. The standard entropy of ions in an aqueous solution was calculated by four independent methods.

Standard and transformed values of gibbs energy formation for some radicals and ions involved in biochemical reactions.

The standard and transformed values of the Gibbs formation function of a number of radicals and ions are calculated: H, OH, HO2,O, SH, NH2, CH3, H+,O-,OH-HO2-, O2-,SH-NH2-, Q-, NAD*, FMN-, FAD-. These data can be used in consideration of the thermodynamics of biochemical reactions involving free radicals.

[Systems with a concentration gradient have no potential energy but have the ability to do useful work].

The systems with the concentration gradient have no potential energy for heat and useful work production. Nevertheless, they have the ability to do useful work due to the heat dragged from the environment using, for instance, electrodes in the concentration cells. The second law of thermodynamics is not violated: work process occurred due to the heat dragged from the environment is coupled with the process of concentration leveling.

[On the possibility of formation in water of OH radical from the hydroxyl ion].

formation of OH- radical from the hydroxyl ion in waterthe The enthalpy and free energy of have been calculated. It has been shown that this reaction cannot take place.

Influence of plants on the methane emission from sediments.

The previous theory [Chem. Global Change Sci. 3 (2001) 33; Chemosphere 50 (2003) 191] of methane emission is applied to vegetated sediments. The presence of roots in a sediment is taken into account. It is assumed that methane and nitrogen enter a sediment through channels existing in plants and roots. The rate of methane and nitrogen transport through plants and roots is proportional to the difference in concentrations in the layer and on the upper surface. It is established that as the vegetation density increases, the rate of methane transport increases so that with sufficient vegetation density, almost all methane passes to the atmosphere through plants. In this case, the value of bubble emission decreases to zero. The nitrogen transport rate through plants first increases and then decreases with increasing the vegetation density. The theory qualitatively and quantitatively describes the dependence of methane concentration on depth in the presence of plants. A comparison with the available experimental data on dissolved methane concentration and bubble composition indicates satisfactory agreement.

Theoretical consideration of methane emission from sediments.

A stationary theory of gas emission from sedimentary (active) layers of wetlands is developed. The theory takes into account methane generation in a sedimentary layer (W1) and its depth dependence, (W1(z)), the solubility, determined by Henry's constant (K1), and the mobility of methane molecules set by the methane diffusion coefficient (D1). The exponential dependence of methane generation rate decay with depth is considered in more detail. The penetration of atmospheric nitrogen into the active layer is also taken into consideration. It is shown that the value of diffusion methane flux from sedimentary layers is proportional to square root(K1D1P0W10) where P0 characterizes the atmospheric pressure and W10 characterizes the maximum generation rate. Coefficients relating the diffusion methane flux to the square root(K1D1P0W10) value are calculated for the different depth dependencies of methane generation rate. The values of these coefficients are not much different from unity for most real cases.

Processes of luminescence quenching in study of molecular oxygen diffusion in glassy matrices.

The methods have been developed for studying oxygen mobility by donor quenching in solutions with uniform concentration and in geminate pairs in a solid phase. It is shown that the kinetics of luminescence variations with time is described by a diffusion model. Oxygen mobility has been studied at low temperatures (77 K) in hard polymer matrices. squalane. glasses of low-molecular hydrocarbons and alcohols. The methods can be used to measure very low oxygen mobility with a diffusion coefficient of about 10(-23) cm2 s(-1).

Methane emission from lakes.

A physico-chemical model to describe methane and carbon dioxide emission from lakes was developed. The model describes the emission by diffusion, bubbles and plants. The intensity of the fluxes can be calculated either for total or particular emission in dependence on gas bubbles composition. It was found, that diffusional (Q) and bubble (J) fluxes depend on the methane molar ratio (X) in bubbles as follows: [formula: see text]. The model allows to estimate the role of the methane oxidation by atmospheric oxygen in the total methane flux. It was shown, that the methane oxidation does not influence much methane fluxes to the atmosphere for most of the experimentally observed situations.

Microsomal and photochemical oxidation and reduction of 1-piperidinoanthraquinone.

In microsomes of control Wistar rats, NADPH-dependent reduction of 1-piperidinoanthraquinone (1-PA) to the corresponding hydroquinone, in the absence of oxygen, has been observed. Two facts ((i) inhibition of the formation of 1-piperidinoanthrahydroquinone (1-PAH) by metyrapone and antibodies to cytochrome P-450, and (ii) increase in the rate of 1-PAH formation upon induction of rats by phenobarbital) indicate that cytochrome P-450 participates in the reduction of 1-PA. Since 1-PA is a substrate of cytochrome P-450 and is oxidized in microsomes to (N-anthraquinonyl-1)-delta-aminovaleric acid (AAV), model experiments have been conducted to examine whether the reduced forms of 1-PA are involved in its oxidation. During photochemical generation of 1-PAH and its subsequent oxidation (N-anthraquinonyl-1)-delta-aminovaleric aldehyde (AAVal) is formed. However, this product is formed without participation of activated form of the substrate and oxygen. AAVal is a substrate in photochemical systems, apparently, is a precursor of AAV in microsomal oxidation of 1-PA. AAVal is substrate of cytochrome P-450 (the Type 1 of binding) and is oxidized quantitatively in microsomal systems to yield AAV. The date obtained enable us to propose a possible mechanism of enzyme oxidation of 1-PA.