Showing papers in "Biofizika in 2015"
Journal Article•
TL;DR: The history of the major discoveries, shows the chronology of the changes in attitudes, trends and paradigms, and the characteristics of radioprotective agents such as a dose reduction factor, time of administration, tissue specificity, toxicity are described.
Abstract: The search for ideal protective agents for use in a variety of radiation scenarios has continued for more than six decades This review describes the history of the major discoveries, shows the chronology of the changes in attitudes, trends and paradigms The readers are invited to meet with various classes of chemical compounds that have the potential to protect against acute and late effects of ionizing radiation when administered either before or after radiation exposure The work represents characteristics of radioprotective agents such as a dose reduction factor, time of administration, tissue specificity, toxicity; the mechanisms of their action and practical applications are also described A separate chapter considers the further development prospects and directions in this field of research
15 citations
TL;DR: In the present work, it has been shown that isolated mitochondria can undergo transformation to lipofuscin granules without any additional factors (oxygen saturation or prooxidants) and the use of a detergent that is able to degrade mitochondria is necessary to measure the lip ofuscin content properly.
Abstract: In the present work, it has been shown that the isolated mitochondria can undergo transformation to lipofuscin granules without any additional factors (oxygen saturation, prooxidants). The process occurs spontaneously and slowly at low temperature, and rapidly--by heating (thermo-lipofuscin) or under UV irradiation (photo-lipofuscin). The main contribution to the formation of mitochondrial lipofuscin comes from denatured proteins. Thermo-formation of lipofuscin depends on lipid peroxidation, while the presence of lipids is not required for photo-lipofuscin formation. It is shown that the use of detergent able to degrade mitochondria is necessary to measure lipofuscin content properly.
15 citations
TL;DR: The optical activity of DNA liquid-crystalline dispersions was studied in the context of the theory of electromagnetic-wave absorption by large molecular aggregates and the effect that the interaction between nucleic acid molecules and nanoparticles exerts on the optical properties of a dispersion.
Abstract: The optical activity of DNA liquid-crystalline dispersions was studied in the context of the theory of electromagnetic-wave absorption by large molecular aggregates. The study also focused on the effect that the interaction between complexes of nucleic acid molecules and nanoparticles exerts on the optical properties of a dispersion.
15 citations
TL;DR: A method to analyze the chlorophyll fluorescence transient was developed using approximation of the experimental signal by a multi-exponential series and gave more rigid criteria of phase identification as compared with the current semi-empirical approach.
Abstract: The method for analysis of chlorophyll fluorescence transient using approximation of measured signal by multi-exponential series is described. Visualization of partial sums of this series allows us to find amplitudes and characteristic times of individual phases of fluorescence induction curve. This method gives more rigid criteria of phase identification instead of semi-empirical approach currently used. Applied to Chlamidomonas reinhardtii sulfur deprivation case, it shows efficiency in finding visually undistinguishable phases of fluorescence transient for early detection of stress.
15 citations
TL;DR: The application of Brownian dynamics for simulation of transient protein–protein interactions is reviewed, and the role ofBrownian-dynamics simulations in studying photosynthetic electron transport is focused on.
Abstract: The application of Brownian dynamics for simulation of transient protein–protein interactions is reviewed. The review focuses on the theoretical basics of the Brownian-dynamics method, its particular implementations, and the advantages and drawbacks of this method. The outlook for future development of Brownian dynamics-based simulation techniques is discussed. Special attention is given to analysis of Brownian dynamics trajectories. The second part of the review is dedicated to the role of Brownian-dynamics simulations in studying photosynthetic electron transport. Interactions of mobile electron carriers (plastocyanin, cytochrome c
6, and ferredoxin) with their reaction partners (cytochrome b
6
f complex, photosystem I, ferredoxin:NADP reductase, and hydrogenase) are considered.
13 citations
Journal Article•
TL;DR: The analysis of the Cancer Genome Atlas RNA-Sequencing data revealed the prevalence of the down-regulation of HK2 gene and only slight expression alterations in HK1 gene, which could be explained by common deregulation mechanisms of these genes in colorectal tumors.
Abstract: One of the hallmarks of cancer is the change of energy metabolism, mainly activation of glycolysis that occurs even at early stages of tumorigenesis. The glycolysis activation can be caused by overexpression of hexokinases, primarily HK1 and HK2. Colorectal cancer, which takes the third place in the cancer morbidity and mortality rates worldwide, is believed to be accompanied with overexpression of HK2, which is .considered a marker of poor prognosis. With the use of the developed CrossHub tool, we performed the analysis of the Cancer Genome Atlas RNA-Sequencing data, which, on the contrary, revealed the prevalence of the down-regulation of HK2 gene and only slight expression alterations in HK1 gene. The Cancer Genome Atlas is the largest resource in the field of molecular oncology that accumulated genomic, transcriptomic and methylomic data for thousands of sample of more than 20 cancers. The transcriptome analysis data for colorectal cancer (283 tumor samples and 41 matched normal samples) were in accord with the results of further qPCR expression level evaluation. Up-regulation of HK1 and HK2 genes was observed only in a part of samples: 12% for HK1 and 30% for HK2. At the same time, the HK2 mRNA level decrease was shown in 50% of cases. Correlation analysis revealed the consistency in HK1 and HK2 expression alterations (Spearman's rank correlation coefficient r(s) = 0.43, p < 0.01), that could be explained by common deregulation mechanisms of these genes in colorectal tumors. The HK3 expression level was significantly increased in 60% of samples. Most likely, just hexokinase 3 contributes significantly to the activation of glycolysis in colorectal cancer.
13 citations
TL;DR: The relationships between the geometric parameters of the tubular leaflet apparatus and its functional characteristics have been analyzed and can be used to develop new models of the Leaflet apparatus for transcatheter prosthetic heart valves or for evaluation of existing designs.
Abstract: This paper presents the analysis of relationships between geometrical parameters of the tubular leaflet apparatus and its functional characteristics. In addition, the degree of the influence of deformation of different zones of leaflets on its ability to perform its function is evaluated in this work. The outcomes of this study could be helpful in developing new models of the transcatheter prosthetic heart valves leaflet apparatus or analyzing existing in-clinical transcatheter aortic valve implantation prostheses.
12 citations
TL;DR: The possibility of using the method of electroacoustic analysis to determine the spectrum of lytic activity of bacteriophages has been shown for the first time and can be used to develop a new express method for determining the sensitivity of microbial cells to bacter iophages.
Abstract: The changes in the electro-acoustic parameters of cell suspension due to the interaction of cells with bacteriophages both in a pure. culture and in the presence of extraneous microflora were investigated. It has been found that the specific changes in the electroacoustic parameters of cell suspension under the action of bacteriophage occur only in microbial cells which are sensitive to the bacteriophage studied. It has been established that a sensor unit allows of distinguishing a situation when the bacterial cells are infected with specific bacteriophages of the control experiments and a situation with no introduction of infection. An approximate criterion of the presence of specific interactions of bacteriophages and cells in suspension was developed. In accordance with this criterion the change in electrical impedance of the sensor unit must not be less than - 1%. In control experiments a standard microbiological technique, plating the cells infected with bacteriophages on solid nutrient medium, was used. For the first time the possibility of using the method of electroacoustic analysis for determination of a spectrum of lytic activity of bacteriophages was shown. The results obtained may be used for development of a new express method for determining the sensitivity to bacteriophages of the microbial cells.
11 citations
Journal Article•
TL;DR: The data obtained suggest an explanation of non-stoichiometric nature of neutralization of reactive oxygen species by derivatives of fullerenes, as well as provide new insight into the physical meaning of the work on the impact of nanoparticles at ultra-low concentrations on biological objects.
Abstract: In this work, we investigated the effect of dilution on aggregation of nanoparticles of the polycarboxylic derivative of fullerene C60. It is shown that the diminution of the concentration of PCDF-1 in aqueous medium leads to a decreased amount of aggregates of fullerene and an increased amount of single molecules. This can potentially interfere with the biological activity of a compound on one molecule basis. Addition of organic and inorganic salts to the aqueous medium with fullerene derivative leads to intense disaggregation of PCDF-1. The data obtained suggest an explanation of non-stoichiometric nature of neutralization of reactive oxygen species by derivatives of fullerenes, as well as provide new insight into the physical meaning of the work on the impact of nanoparticles at ultra-low concentrations on biological objects.
7 citations
TL;DR: The results are interpreted on the basis of the inhibiting action of sodium fluoride on phosphatase and its effect on chlorophyll excitation energy redistribution between photosystems II and I, and the negative impact of fluoride on the ATPase complex and Calvin–Benson cycle, on the other hand.
Abstract: It is shown that the treatment of bean leaves with NaF in concentration of 10(-2) M resulted in the alteration of fluorescent indices registered by the method of pulse fluorimetry Fluorescent parameters F(0) and F(m) decreased, but the ratio F(v)/F(m) = (F(m) - F(0))/F(m), characterizing the maximal photochemical activity of photosystem II remained invariable Photochemical fluorescence quenching (qP) was higher than in control during the first minutes of illumination with the actinic light, and it markedly decreased with the following illumination Nonphotochemical quenching (qN), in contrary, decreased at the beginning of illumination, and then increased Photosynthetic activity as characterizing by the ratio (F(M) - F(T))/F(T) reduced after the leaf treatment with NaF Results obtained are interpreted proceeding, on the one hand, from the influence of NaF on redistribution of excitation energy between photosystem II and photosystem I and its inhibitory effect on the ATPase complex and Kalvin-Benson cycle, on the other
7 citations
TL;DR: It is shown that interaction of the cellular oscillators provides stable action-potential generation in cardiac pacemaker cells, even in the case of stochastic Ca2+ dynamics.
Abstract: An integrative model of the calcium dynamics in cardiac pacemaker cells is developed taking into account a synergetic effect of the interaction between an outer membrane oscillator and an intracellular calcium oscillator ("membrane and Ca(2+)-clock"). The main feature of the model is a description of the stochastic dynamics of Ca2+ release units within the electron-conformational mechanism of the functioning of ryanodine-sensitive calcium channels. It is shown that interaction of two cellular oscillators provides a stable action potential generation in the cardiac pacemaker cells even in the case of the stochastic Ca2+ dynamics. We studied in detail the effect of ryanodine channels sensitivity to an increase in the intracellular calcium concentration in sarcoplasmic reticulum and in the dyadic space on the behavior of calcium-release system. A parametric analysis of the integrative model of pacemaker cells is performed.
TL;DR: A numerical method is developed for the analysis of particle trajectories in living cells, where the type of movement is determined by Akaike’s information criterion, whereas the model parameters are identified by the weighted least-squares method.
Abstract: We have developed a numerical method for the analysis of particle trajectories in living cells, where a type of movement is determined by Akaike's information criterion, while model parameters are identified by a weighted least squares method. The method is realized in computer software, written in the Java programming language, that enables us to automatically conduct the analysis of trajectories. The method is tested on synthetic trajectories with known parameters, and applied to the analysis of replication complexes in cells, infected with hepatitis C virus. Results of the analysis are in agreement with available data on the movement of biological objects along microtubules.
TL;DR: By modulation of the activity of succinate dehydrogenase, infrared radiation regulates energy production in mitochondria that is provided by the most potent oxidation substrate, viz., succinic acid; the effect is especially pronounced under stress.
Abstract: Biological effects of light near infrared radiation (850 nm), with modulation acoustic frequency of 101 Hz, was studied. The study was conducted on rats, the effect was recorded by succinate dehydrogenase activity in lymphocytes on the blood smear after administration of the activating dose of adrenaline, which simulates the state of the organism in the early stages of the pathogenic effects (stress). A pronounced regulating effect of infrared radiation on the activity of succinate dehydrogenase in animals activated by adrenaline was shown. Infrared radiation has a normalizing effect reducing the degree of inhibition or activation of the enzyme induced by adrenaline and had no effect on the control animals. Thus, by modulating the activity of succinate dehydrogenase infrared radiation regulates energy production in the mitochondria supported by the most powerful oxidation substrate--succinic acid, which is especially pronounced under stress.
TL;DR: Cell-culture experiments showed that liposomal forms of the DME and TME derivatives of Chl e6 had significantly lower cytotoxicity, while preserving a high cytotoxic effect of photodynamic activity.
Abstract: Photophysical characteristics and photosensitizing activity of the chlorin e6 dimethyl and trimethyl ester derivatives in various solution and their liposomal forms were studied. It was shown that in lipid vesicles chlorin e6 ester derivatives are predominantly in the monomeric state and possess optimal photophysical properties and high photochemical activity. The rate of redistribution of the chlorin e6 dimethyl ester from lipid vesicle to cells was higher as compared with that one of the chlorin e6 trimethyl ester. The increase of the serum concentration in the incubation medium has a different effect on processes of accumulation of the liposomal forms of the chlorin e6 dimethyl and trimethyl ester derivatives by the cells. Cell culture studies showed that application of liposomal forms of the chlorin e6 dimethyl and trimethyl ester derivatives significantly decreases their cytotoxicity but keeps high cytotoxic effect of photodynamic activity of the chlorin e6 ester derivatives.
Journal Article•
TL;DR: It was found that the rate of ATP synthesis decreases after addition of various agents that increase the medium viscosity (sucrose, dextran 40 or polyethylene glycol 6000) provided that these agents cause neither uncoupling nor electron transport inhibition in the absence of ADP.
Abstract: The effect of an increase in the medium viscosity on cyclic photophosphorylation in chloroplast thylakoids and on Ca2+ -dependent ATP hydrolysis by the chloroplast coupling factor CF, was studied. With 0.1-0.2 mM ADP used it was found that the rate of ATP synthesis decreases after addition of various agents that increase the medium viscosity (sucrose, dextran 40 or polyethylene glycol 6000 provided that these agents cause neither uncoupling nor electron transport inhibition in the absence of ADP. Dextran and polyethylene glycol inhibited ATP synthesis by 50% when their concentrations were much lower (6-10%) than that of sucrose (30-40%), while 50% inhibition of Ca2+ -dependent ATP hydrolysis by CFI-ATPase was observed at higher concentrations of dextran and polyethylene glycol (9-13%) and lower concentrations of sucrose (about 20%). For ADP, the effective Michaelis constant (KM) was shown to increase 2-3-fold with the increasing viscosity; meanwhile the maximal rate of cyclic photophosphorylation remained virtually unchanged. The dependence of K(M) on the medium viscosity can serve as a criterion for the process of diffusion-controlled photophosphorylation. Possible mechanisms of ADP and ATP diffusion are discussed.
TL;DR: It was demonstrated that, depending on the increment (jump) of the partial expansion coefficient and the change of the Transition temperature, the enthalpy of the transition can either increase or decrease with pressure, and it was also shown that when the pressure increases the changes in the volume andEnthalpy under denaturation cannot change their signs.
Abstract: Possible effects of high pressure on heat denaturation of biopolymers have been analyzed. The study was made using an equilibrium model of transition between two states. Equations used to determine the dependence of thermodynamic parameters of transition (enthalpy, entropy and transition temperature) on pressure were formulated. Pressure may have both stabilizing and destabilizing effects on the macromolecule structure depending on the change in the volume upon transition. The dependence of the transition temperature on pressure cannot have local extremums. It is demonstrated that depending on the increment (jump) of the partial expansion coefficient and the change of the transition temperature, the enthalpy of transition can both grow with the pressure growth or decrease. It is also .shown that when the pressure grows, the changes in the volume and enthalpy under denaturation cannot change their signs.
TL;DR: The results of different experiments concerning the embryonic development of fish, amphibians, birds, and mammals under microgravity conditions are presented and possible causes of the observed morphological changes are discussed.
Abstract: The review is devoted to various aspects of early development under the space flight conditions. The different possible cell mechanosensors are considered. Structural and functional changes in the cells, predominantly, in non-muscle ones, were discussed. The results of the different experiments with the embryos of fish, amphibians, birds and mammals under microgravity conditions are shown discussing possible reasons for the development of morphological changes.
TL;DR: The suppression of resistance in acute myeloid leukemia cells to TRAIL-induced apoptosis in multicellular aggregates was studied using small molecular inhibitors of the activation of the transcription factor NF-kB, viz.,NF-kB Activation Inhibitor IV and JSH-23 at nontoxic concentrations.
Abstract: Suppression of resistance in acute myeloid leukemia cells to TRAIL-induced apoptosis in multicellular aggregates, was studied using small molecule inhibitors of the activation of the transcription factor NF-kB - NF-k9 Activation Inhibitor IV and JSH-23 at non-toxic concentrations. NF-kB Activation Inhibitor IV and JSH-23 reduced resistance in the acute myeloid leukemia cells in multicellular aggregates to cytotoxic action of recombinant protein izTRAIL. It is shown that the use of these inhibitors decreased the phosphorylation of the RelA (p65) as a main marker activation of the transcription factor NF-kB. We discuss a possible reason for increasing resistance in acute myeloid leukemia cells to TRAIL-induced apoptosis in multicellular aggregates.
TL;DR: Comparison of all of the data revealed a high probability of the existence of both “local” positional order and “long-range” orientation order in the arrangement of double-stranded DNA molecules in both the liquid-crystalline phase and a dispersion of particles of this phase formed under certain conditions.
Abstract: The answer to a question on the organization of molecules in a cholesteric phase is well enough proved in case of low molecular mass compounds. However, in case of double-stranded nucleic acids molecules the unequivocal answer to such question is a subject of discussions. In this work an attempt to generalize the well known literary data on the structure of the cholesteric phase formed by double-stranded DNA molecules was undertaken. Besides the experimental results of authors describing the packing of these molecules in the cholesteric liquid-crystalline dispersion particles are added to these data. Comparison of the results obtained offers the possibility to come out with an assumption of high probability of the existence of both the short-range positional and long-range orientational order in arrangement of double-stranded DNA molecules in a liquid-crystalline phase, and in the particles of dispersions of this phase generated under certain conditions. The occurrence of the orientational order, i.e. rotation of 'quasinematic' layers of double-stranded DNA molecules by a small angle, defines the formation of spatially twisted (cholesteric) structure with characteristic for it physical and chemical properties.
TL;DR: This review summarizes the available published data on the role of cGMP in the responses of plants to stressors of abiotic and biotic natures and its interaction with other intracellular mediators.
Abstract: Currently, biophysical mechanisms of stress signaling transduction became an object of consideration of researchers in connection with the urgent necessity to develop new techniques to enhance the sustainability and productivity of agricultural crops. The development of sensitive methods for the determination of cyclic guanosine monophosphate (cGMP) and comparative analysis of cGMP-dependent events in biological systems has contributed to progress in the understanding of the functioning of cGMP in plant cells. Currently, it is shown that cGMP as a secondary mediator is involved in such vital processes of growth and development of plants as seed germination, cell division, development of chloroplasts, flowering and regulation of stomatal movements. This review summarizes the available data in the literature about the role of cGMP in the responses of plant organisms to the action of stress factors of abiotic and biotic nature and its interaction with other intracellular mediators. With the use of existing ideas about the biophysical mechanisms of stress in plants, the basic elements of cGMP-dependent signal transduction system in a plant cell are considered.
TL;DR: It was hypothesized that an increase in the degree of titin phosphorylation results in increased proteolytic degradation of this protein, which contributes to the development of skeletal muscle atrophy.
Abstract: From our earlier experiments on the study of changes in titin content and the level of its phosphorylation in skeletal muscles, atrophied during space flight, hibernation, and also because of the development of alcohol-induced lesions it has been suggested that an increase in the degree of titin phosphorylation results in increased proteolytic degradation of this protein, that contributes to the development of skeletal muscle atrophy.
TL;DR: It was shown that the presence of AgNO3 leads to both an increase in the main phase transition temperature (Tm) of DPPC multibilayers and the appearance of an additional phase transition peak (T’m), suggesting an increased in both the density and heterogeneity of the lipid bilayer.
Abstract: In order to study the effects caused by silver nitrate (AgNO3) on model lipid membranes, we studied multibilayer membranes based on L-α-dipalmitoylphosphatidylcholine (DPPC) and AgNO3 aqueous soluitions in a wide concentration range (up to 30 wt%) by means of differential scanning calorimetry It has been shown that the presence of AgNO3 leads both to an increase in the main phase transition temperature (T(m)) and appearance of an additional phase transition peak (T(m)), suggesting increasing of both density and heterogeneity of the lipid membrane The effect of nitrate ions (NO ) was shown to be of the opposite nature (bilayer fluidizing), so the integral densifying effect of AgNO3 can be referred solely to the action of silver ions (Ag(+)) With increasing AgNO3 concentration, the tendency was observed to opposite changes in T(m) and T'(m) peaks intensity, thereby at about 26 wt% of AgNO3 the initial peak (T(m)) disappeared In the range of Ag+ therapeutic concentrations (up to 2 wt%) no significant changes in the DPPC membrane were revealed This can be one of the reasons of the absence of a damaging effect of silver drugs on a host organism with simultaneous pronounced bactericidal effect
TL;DR: Analysis of the deviations between the trajectories of the Lotka–Volterra model for competition between two species and Gause’s experimental data on cocultivation of Paramecium aurelia and P. caudatum demonstrates rather a high probability of the absence of any correspondence between the model and experimental data.
Abstract: Analysis of deviations between trajectories of Lotka-Volterra model of competition between two species and G.F. Gause experimental time series on combined cultivation of Paramecium aurelia and Paramecium caudatum shows that with rather big probability there is no correspondence between model and experimental datasets. Testing of sets of deviations was provided on symmetry with. respect to origin (Kolmogorov-Smirnov, Lehmann-Rosenblatt, Wald-Wolfowitz, and Munn-Whitney criterions) and on existence/absence of serial correlation in sequences of residuals (Swed-Eisenhart and "jumps up-jumps down" tests).
Journal Article•
TL;DR: Increased expression of IL-6, IL-8, TNF-α and p53 genes under the nanoparticles action indicates the stimulation of the immune system and of apoptosis, respectively.
Abstract: In order to evaluate the toxic effect of silver (AgNP) and titanium dioxide (TiO2) nanoparticles their influence on the expression of genes of biomarkers of inflammatory responses and apoptosis in human lymphocytes was studied. An increase in the IL-6, IL-8, TNF-α and p53 genes expression in the concentration range of silver and titanium dioxide nanoparticles of 10-40 μk g/ml was found. Increased expression of IL-6, IL-8, TNF-α and p53 genes under the nanoparticles action indicates the stimulation of the immune system and of apoptosis, respectively.
TL;DR: It was shown that the changes in these parameters at the same power dose depended on both the individual initial level of venous blood hemoglobin oxygen saturation and the photoinduced changes in blood, which objectively reflect the individual sensitivity of patients to the action of optical radiation on blood and can be used for the assessment of the efficiency of phototherapy.
Abstract: The effect of in vivo laser irradiation by optical radiation on blood from different patients is studied. The objects of research were three series of blood samples from patients whose treatment course included extracorporeal UV blood irradiation, intravenous laser blood irradiation and supra-venous blood laser irradiation. Before and after irradiation the results on optic oximetry and gas content of venous blood were compared. The results of positive and negative influence of blood irradiation on characteristics of an oxygen exchange in separate patients and on the maintenance of some products of metabolism are represented. It is shown that at the same power dose, their changes depend on individual, initial values of hemoglobin oxygen saturation of venous blood and its photoinduced changes which objectively reflect individual sensitivity of patients to the action of optical radiation on blood and can be used for assessment of the efficiency of phototherapy.
Journal Article•
TL;DR: It is shown that microbial metabolites of phenolic nature have an inhibitory effect on the activity of dehydrogenases, determined by the reduction of dichlorophenolindophenol and nitroblue tetrazolium in liver mitochondria and liver homogenates.
Abstract: The aim of this work was to study the effect of microbial metabolites of phenolic nature on the activity of enzymes of the tricarboxylic acid cycle in isolated mitochondria, and determine metabolites of the tricarboxylic acid cycle as potential biomarkers of mitochondrial dysfunction in the blood of patients with sepsis. It is shown that microbial metabolites of phenolic nature have an inhibitory effect on the activity of dehydrogenases, determined by the reduction of dichlorophenolindophenol and nitroblue tetrazolium in liver mitochondria and liver homogenates. This effect is more pronounced in oxidation of the NAD-dependent substrates than succinate oxidation, and at lower concentrations of microbial metabolites than inhibition of respiration. By gas chromatography-mass spectrometry it was found that the content of the tricarboxylic acid cycle metabolites in the blood of patients with sepsis decreased compared to healthy donors. The data obtained show that the microbial phenolic acids can contribute significantly to the dysfunction of mitochondria and suppression of general metabolism, characteristic of these pathologies.
TL;DR: The coefficient of friction (COF) is obtained in a general exponential form that is characteristic of a virtually infinite level of the interaction map, but its application to a hydration repulsion bilayered system that is prone to facilitated lubrication is taken as linearly confined.
Abstract: An extension of the Coulomb-Amontons law is proposed in terms of an interaction-detail involving renormalization (simplified) n-th level scheme. The coefficient of friction is obtained in a general exponential (nonlinear) form, characteristic of virtually infinite (or, many body) level of the interaction map. Yet, its application for a hydration repulsion bilayered system, prone to facilitated lubrication, is taken as linearly confined, albeit with an inclusion of a decisive repelling force/pressure factor. Some perspectives toward related systems, fairly outside biotribological issues, have been also addressed.
TL;DR: It was observed that 100 mM proline does not show any significant stabilization to either DHFRs and the human protein is relatively less stable than the E. coli counterpart.
Abstract: A protein, differing in origin, may exhibit variable physicochemical behaviour, difference in sequence homology, fold and function. Thus studying structure-function relationship of proteins from altered sources is meaningful in the sense that it may give rise to comparative aspects of their sequence-structure-function relationship. Dihydrofolate reductase is an enzyme involved in cell cycle regulation. It is a significant enzyme as.a target for developing anticancer drugs. Hence, detailed understanding of structure-function relationships of wide variants of the enzyme dihydrofolate reductase would be important for developing an inhibitor or an antagonist against the enzyme involved in the cellular developmental processes. In this communication, we have reported the comparative structure-function relationship between E. coli and human dihydrofolate reductase. The differences in the unfolding behaviour of these two proteins have been investigated to understand various properties of these two proteins like relative' stability differences and variation in conformational changes under identical denaturing conditions. The equilibrium unfolding mechanism of dihydrofolate reductase proteins using guanidine hydrochloride as a denaturant in the presence of various types of osmolytes has been monitored using loss in enzymatic activity, intrinsic tryptophan fluorescence and an extrinsic fluorophore 8-anilino-1-naphthalene-sulfonic acid as probes. It has been observed that osmolytes, such as 1M sucrose, and 30% glycerol, provided enhanced stability to both variants of dihydrofolate reductase. Their level of stabilisation has been observed to be dependent on intrinsic protein stability. It was observed that 100 mM proline does not show any 'significant stabilisation to either of dihydrofolate reductases. In the present study, it has been observed that the human protein is relatively less stable than the E.coli counterpart.
Journal Article•
TL;DR: A comparative study of antioxidant (radical-interceptor) properties of tryptanthrin in the systems of 2,2'-azo-bis(2-methylpropionamidin)dihydrochloride-luminol and hemoglobin-hydrogen peroxide- luminol has been conducted and the influence on the permeability of planar bilayer lipid membranes is evaluated.
Abstract: A comparative study of antioxidant (radical-interceptor) properties of tryptanthrin (quinazoline alkaloid shows a high anti-inflammatory activity and it is found in many types of different families of higher plants and microorganisms, including the human microbiome) in the systems of 2,2'-azo-bis(2-methylpropionamidin)dihydrochloride-luminol and hemoglobin-hydrogen peroxide-luminol has been conducted and the influence on the permeability of planar bilayer lipid membranes is evaluated. Trolox was used as a reference antioxidant, and ascorbic acid and dihydroquercetin were taken as standards. Tryptanthrin exhibits very weak antioxidant activity, being markedly inferior to the reference standard and antioxidants while testing antioxidant activity in both studied systems. By the efficacy of antioxidative action the substrates in the systems studied can be arranged in the following order: dihydroquercetin > trolox > ascorbic acid > tryptanthrin. Antioxidant potential of tryptanthrin is approximately 1000 and 3000 times lower than that of trolox and bioflavonoid dihydroquercetine, respectively. Tryptanthrin causes no significant changes in the permeability of planar bilayer membranes in a dose range of 0.5 to. 10 μg/ml. Our data show that tryptanthrin displays no significant radical-interceptor and membranotropic activities. It can be assumed that the observed high anti-inflammatory activity of tryptanthrin is not related to the neutralizing effect against reactive oxygen species and the influence on the permeability of cell membranes. The anticipated mechanisms of biological activity of tryptanthrin are discussed.
TL;DR: This study has complemented the already described period-tripled model with the periods of human memory performance, also adding seven relevant periods/frequencies of the period-Tripled model in the range of human hearing, and arrived at the conclusion that these characteristic frequencies may form a basis of music and singing phenomena.
Abstract: A recent paper by S.J. Puetz et al. (Chaos, Solitons -& Fractals, v. 62-63, p. 55, 2014) described a fundamental period-tripled model. It involves periods of different astronomical (quasars, Sun), geophysical (geomagnetic, climatic, volcanic) and some biological processes. This work contains statistics for sixteen pairs of a period-tripled sequence. These periods range from -50 years to 1.5 billion years and no signs of the timescale limitations are found. We believe that the universal scope of the fundamental period-tripled model can be used for the development of new methodology of research data analysis: the main idea is that the spectrum of the periods of the studied event should be tested for the similarity with the spectrum of fundamental period-tripling pattern (because of the fundamental nature of the period-tripled model). Using this method, in this study we complement an already described period-tripled model with periods of human memory performance ranging from one minute to one month also adding seven relevant periods/frequencies of the period-tripled model in the range of human hearing. We make a conclusion that these characteristic frequencies may form the basis for music and singing phenomena. The new methodology is particularly appropriate for being applied in medicine and engineering.