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At least 19 recordsLinked to original sources

PubMed1975

Thermodynamical studies of oxygen equilibrium of hemoglobin. Nonuniform heats and entropy changes for the individual oxygenation steps and enthalpy-entropy compensation.

Precise oxygen equilibrium curves of human adult hemoglobin were determined by the automatic recording method at several temperatures in the presence and absence of 2,3-diphosphoglycerate (DPG) or inositol hexaphosphate (IHP) with 0.05 M 2,2-bis(hydroxymethyl)-2,2',2''-nitrolotriethanol (bis-tris) buffers (pH 7.4) containing 0.1 M Cl-. The equilibrium data were analyzed according to the Adair scheme, and the heats, deltaHi (i = 1,2,3,4) and the entropy changes, deltaSi (i = 1,2,3,4), for the individual oxygenation steps were obtained. The shape of the equilibrium curve varies on temperature changes whether DPG or IHP is present or absent. In consequence, the deltaHi value depends on i and on the presence of DPG and IHP. Behavior of deltaSi is similar to that of deltaHi. The similar behavior of deltaHi and deltaSi resulted in a compensation phenomenon. The contribution of T cdeltaSi to the free energy change is compensated by the contribution of deltaHi at the first three oxygenation steps but not at the fourth step, and for i = 1,2, and 3 changes of T cdeltaSi value upon the addition of DPG and IHP are compensated by accompanied changes of deltaHi value, where T c (= 260 K) is the compensation temperature. A major part of both the enthalpy-entropy compensation and nonuniformity of deltaHi and deltaSi appears to be attributable to contributions of the oxygen-linked binding of Cl-, DPG and IHP, by hemoglobin. The present results do not necessarily support the earlier idea of Wyman that the cooperative oxygenbinding is essentially an entropy effect.

Adult↗

PubMed2026

Tissue-Level Transcriptomic Entropy Reveals Organ-Specific Aging Patterns and Predicts Cancer Progression.

Although aging and cancer share complex molecular mechanisms, distinguishing causative factors from byproducts remains challenging. Here, we investigated the role of tissue transcriptomic entropy-a measure of transcriptional disorder-in aging and cancer processes by analyzing RNA-sequencing data from over 25,000 samples from human and mouse tissues. We found that entropy changes during aging are highly tissue-specific, with some tissues showing increased entropy while others exhibit decreased or stable entropy levels. Moreover, transcriptomic entropy strongly correlates with age-related processes, showing positive associations with proliferation, cellular senescence, somatic mutation burden, and cellular reprogramming, whereas it negatively correlates with stemness. In cancer, we observed that primary tumors generally display higher entropy than normal tissue, with its levels further increasing in metastatic stages. Cancer treatment modulated entropy patterns in multiple contexts, with changes suggesting a role for transcriptional complexity in tumor plasticity and therapy resistance. Elevated entropy levels predicted poor survival outcomes in multiple cancer types, suggesting its potential as a prognostic marker. Furthermore, differential expression analysis revealed that entropy-associated genes are enriched in developmental processes and depleted in metabolic pathways, indicating a possible link to cellular dedifferentiation. Finally, we found increased entropy in various age-related disorders beyond cancer, suggesting that transcriptomic entropy may be a common feature in age-related diseases. Our findings establish transcriptomic entropy as a fundamental parameter in aging and cancer progression, offering new insights into disease mechanisms.

Humans↗

PubMed1977

Public nuisance and entropy increase.

Public nuisance if the inevitable physical conclusion of the second law of thermodynamics, the increase of entropy, under which humans make efforts to build up order, that is, to make states of lower entropy, scattering much entropy into the environment. In other words, humans live on negentropy, negative entropy. Saving of negentropy is the first means of conserving the environment. Soon after C. E. Shanon had introduced the idea of entropy in information theory, N. Wiener showed the relation between entropy of thermodynamics and entropy of information. Wiener showed that the paradox of Maxwell is not a contradiction if we consider the entropy of demon's information. This idea is very suggestive. Moral principles, tax systems, and price mechanisms are effective for the conservation of the environment. Good information systems can conserve good environments. This is the second means. The third way is the use of biological systems. For example, in sewage treatment plants the active sludge purifies polluted water. The reason why microorganisms can select some substances in polluted water is that they have received the information by heredity, the information carried by the double helical structure of DNA.

Environment↗

PubMed2026

Research on multi-trait genome association study method based on Shannon information entropy.

BACKGROUND: Genetic analysis of complex traits is crucial for elucidating disease mechanisms and biological inheritance processes. However, traditional Genome-wide Association Study (GWAS) for single trait often fail to capture the synergistic effects of genetic loci on multiple traits. METHODS: This study proposes a method for analyzing the association between multiple traits and gene regions based on Shannon information entropy. Innovatively, Shannon information entropy is introduced to integrate gene region information as genetic entropy, thereby constructing an Inverse Shannon Entropy-Multi-Trait Association Analysis of Gene Region genetic model (InvSE-MTAGR). Furthermore, a partial regression test is applied to the model to establish the Inverse Partial Shannon Entropy-Multi-Trait Association Analysis of Gene Region method (InvPSE-MTAGR). When performing multi-trait analysis with InvSE-MTAGR, the method achieved statistical significance by accumulating minor effects, thereby enhancing the ability to identify pleiotropic gene regions. RESULTS: The simulation results showed that the proposed multi-trait gene region association analysis method performed well in terms of both Type I error rate control and statistical power. Leveraging tomato and sorghum datasets for validation, the proposed multi-trait gene region association analysis method based on Shannon information entropy accurately pinpointed most of the gene regions harboring candidate genes. CONCLUSION: The study reveals the advantage of multi-trait method in integrating weak-effect pleiotropic signals and capturing the correlation among traits, which provides an efficient theoretical tool for dynamic analysis of complex multi-trait genetic networks and multi-target collaborative breeding of crops.

Genome-Wide Association Study↗

PubMed1978

Rate of polymer formation and entropy production during competitive replication.

The rate of increase in the mean polymer formation rate constant during competitive replication by Qbeta RNA variants (Kramer et al., 1974) has been shown to agree statistically with the variance in their formation rate constants. This result demonstrates that Fisher's fundamental theorem of natural selection (Fisher, 1930) can define time variations in the mean rate of synthesis for a heterogeneous population of replicating polymers. It was also revealed that RNA replication, far from equilibrium, accompanied a progressive decrease in the order of the entropy production derivative, with respect to time, that reached a maximum (with the next higher order being zero). Maximization of entropy at equilibrium, in compliance with the second law of thermodynamics, therefore appears as a natural extension of the earlier non-equilibrium pattern of entropy production within the system. The order of the zero-valued entropy production derivative was shown to be determined by the chemical affinity, and its rate of decrease was specified by the mean polymer formation rate constant.

Biological Evolution↗

PubMed1977

Morphology of branching trees related to entropy.

Analyses of river systems by geomorphologists have suggested that for minimal entropy production in the movement of water down the river the fall in altitude should be equal in each order of branching of the tributaries. In this paper the same concepts have been applied to the bronchial tree and pulmonary arterial tree, assuming that the energy associated with pressure difference is analogous to that associated with altitude difference in rivers. The morphology of the bronchial tree is such that, given laminar flow or air, the calculated pressure difference across each order is equal. This may indicate that the bronchial tree is designed for minimal entropy production. In the arterial tree, however, this result is not obtained, probably because we do not know how to calculate the pressure drop in blood flowing through a branching system. It is therefore not currently possible, on the basis of this approach, to say whether the pulmonary arterial tree is designed for minimal entropy production or not.

Airway Resistance↗

PubMed1975

Dipole moment, enthalpy, and entropy changes of Hodgkin-Huxley type kinetic units.

Dipole moment, enthalpy, and entropy changes were calculated for hypothetical structural units which control the opening and closing of ionic channels in axon membranes. The changes of these thermodynamic functions were calculated both for activation (transition to intermediate complex) and for the structural transformation as a whole. The calculations are based on the experimentally determined Q10 values and the empirical formulae for the rate constants (alpha's and beta's) as functions of membrane potentials in Hodgkin-Huxley type models. From the calculated thermodynamic functions we suggest that the specific structural units of the axon membranes are probably of macromolecular (possible protein-like) dimensions with large dipole moments (hundreds of debyes). The calculated dipole moment changes of a single structural unit indicate that in many cases these dipole moments saturate at strong depolarizations or hyperpolarizations. The transitions in structural units show substantial activation enthalpies and entropies but the net enthalpy and entropy changes are practically negligible for the transition as a whole, i.e. the structural units presumably undergo displacements. While the calculated dipole moment changes associated with structural transformations in Loligo and Myxicola show similar potential dependencies, those for Rana usually show a different behavior. The relevance of the dipole moment changes to gating currents is discussed.

Animals↗

PubMed1979

Temperature coefficients of affinity and entropies of adsorption from enantiomeric pairs of compounds acting at muscarinic receptors in the guinea-pig ileum.

1 The affinities of a series of enantiomeric pairs of esters of phenylcyclohexylglycollic acid, of a pair of esters of alpha-methyltropic acid and of hyoscyamine methiodide have been measured for the muscarinic receptors of the guinea-pig ileum at 30 degrees and 37 degrees C and estimates have been made of their free energies, enthalpies and entropies of adsorption. 2 With (-)-S-hyoscyamine methiodide the enthalpy of adsorption is negative whereas with the (+)-R-enantiomer it is positive. 3 With the esters of phenylcyclohexylglycollic acid the size of the onium group appears to be as important as the stereochemical configuration in determining entropy. Large onium groups appear to be associated with an increase in entropy though this can only be measured approximately because of the narrow range of temperature which can be used.

Adsorption↗

PubMed1977

Enthalpy-entropy compensation in dinitrophenyl--anti-dinitrophenyl antibody interaction(s).

The effect of varying the temperature over a wide range (-3 dergees -67 degrees) on the binding of xi-DNP-L-Lysine to bovine colostral anti-DNA IgG1, and also rabbit anti-DNP IgG revealed non-linear van't Hoff plots. The extent of the curvatures were found to be indicative of large positive heat capacity changes; and the thermodynamic parameters, calculated using a non-linear least-squares computer procedure for these anti-DNP antibody preparations, revealed an enthalpy-entropy compensation mechanism for hapten-antibody binding. The enthalpy factor was found to be the primary contributor for the binding process at low temperatures, but at increasing temperatures the entropy factor assumed greater importance. At physiological temperature (37 degrees), the entropy factor was the major contributor to the free energy of reaction for rabbit anti-DNP IgG, while for bovine colostral anti-DNP IgG it was predominant at temperatures higher than 37 degrees.

Animals↗

PubMed2026

Entropy-Driven Electrolyte Design for Lithium Metal Batteries: Achieving Interfacial Stability With Fluorinated Fullerene Nanoparticle Additives.

Lithium metal batteries are highly attractive for next-generation high-energy-density storage, and ether-based electrolytes such as LiFSI/DME are particularly promising for high-rate operation because of their low viscosity, high ionic conductivity, and favorable compatibility with Li metal. However, current electrolyte optimization strategies still rely mainly on small-molecule additives that regulate bulk solvation or the primary Li+ solvation sheath, whereas entropy-driven modulation of the interfacial solvation environment by large molecular additives remains largely unexplored. Herein, fluorinated fullerene C60F30 (FF) is introduced as a nanoparticle additive to create a dynamically disordered interface that enhances configurational entropy without sacrificing Li+ diffusivity, while accelerating Li+ desolvation and transport. Meanwhile, FF cooperates with FSI--derived species to build a robust fluorine-rich SEI, suppressing dendrite growth and parasitic reactions. As a result, Li||Li symmetric cells cycle stably for 1500 h, while high-loading Li||LiFePO4 cells retain 96.0% capacity after 500 cycles at 2C and 95.9% after 1000 cycles at 10C. Moreover, pouch cells and high-loading Li||NCM811 cells further verify the practical promise of the FF-enabled electrolyte for high-rate, long-cycling LMBs.

Li metal batteries↗

PubMed2026

Quantifying the peripheral surface information entropy from conformational ensembles of globular protein-peptide complexes.

Predicting favorable protein-peptide binding events remains a central challenge in biophysics, with continued uncertainty surrounding how nonlocal effects shape the global energy landscape. Here, we introduce peripheral surface information entropy, SΨ, a quantitative measure of the statistical variability in apolar and charged non-interacting surface (NIS) proportions across conformational ensembles. Within the Gibbs free-energy relation ΔG = ΔH - TΔS, SΨ is proposed as a computationally tractable entropic proxy rather than a direct thermodynamic observable or stand-alone estimator of binding affinity. Using energy-directed molecular docking via HADDOCK3 and explicit-solvent molecular dynamics simulations, it is demonstrated that favorable binding partners exhibit emergent, low-entropy N-states (discrete macrostates in NIS state space) indicative of preferential apolar/charged surface configurations. Across dozens of peptides and multiple receptor systems (WW, PDZ, and MDM2 domains), dominant N-states persisted under varied docking parameters and initial conditions. A meta-ensemble of 657 complexes from 36 experiments over 15 years confirmed the presence of dominant NIS modes independent of in silico methodology, suggesting an evolutionary selection pressure toward specific NIS fingerprints. These findings establish SΨ as a thermoinformatic descriptor that encodes favorable binding constraints into unique statistical signatures of the NIS.

Entropy↗

PubMedDate not supplied

Entropy of the genetic information and evolution.

The entropy of the amino acid sequences coded by DNA is considered as a measure of diversity of variety of proteins, and is taken as a measure of evolution. The DNA or m-RNA sequence is considered as a stationary second-order Markov chain composed of four kinds of bases. Because of the biased nature of the genetic code table, increase of entropy of amino acid sequences is possible with biased nucleotide sequence. Thus the biased DNA base composition and the extreme rarity of the base doublet CpG of higher organisms are explained. It is expected that the amino acid composition was highly biased at the days of the origin of the genetic code table, and the more frequent amino acids have tended to get rarer, and the rarer ones more frequent. This tendency is observed in the evolution of hemoglobin, cytochrome C, fibrinopeptide, immunoglobulin and lysozyme, and protein as a whole.

Amino Acid Sequence↗

PubMed1978

Thermodynamic studies of the interaction of alpha-chymotrypsin with water. II. Statistical analyses of the enthalpy-entropy compensation effect.

Differential enthalpies (deltaH) and entropies (deltaS) of the interaction of water with a high and low temperature conformer of alpha-chymotrypsin were determined previously by multitemperature sorption measurements. The changes in (deltaH) and (deltaS) with water content of the protein were found to show a pronounced compensation pattern. It is known that van 't Hoff data may exhibit enthalpy-entropy compensation, which is entirely due to statistical error propagation. To discriminate between artifactual and significant compensation, the experimental results are analyzed by statistical methods. The results of two different statistical analyses show that a linear, chemically caused compensation effect can be established for the interaction of water with both chymotrypsin conformers. The compensation temperature beta = deltaH/deltaS was found to be 433 +/- 22 K. The compensation effect is detectable only in the water content range above the monolayer volume (upsilonm), computed by the Brunauer, Emmett and Teller equation. This result is discussed in terms of a monolayer hydration mechanism, formulated on the basis of previous thermodynamic results: The interaction of the first water monolayer with the charged and polar surface area of the dry protein, largely stabilizes its tertiary structure. Further water addition then occurs to a practically invariable protein surface. According to this mechanism (which ensures a maximum of conformational stability with a minimum of hydration water), large conformational changes can be expected to occur mainly in the monolayer water content range. This expectation is confirmed by extra-thermodynamic data (infrared and X-ray measurements). The thermodynamic quantities of the sorption process are thus governed by conformational effects below upsilonm. Above the monolayer water content range, however, the water binding process per se strongly predominates. The deltaH/deltaS compensation effect established for this water content range, is thus attributable to phase transitions of water molecules from the gas (or liquid) phase to the protein-bound state (or vice versa). A possible relationship between the linear compensation effect established in this study, and the compensation phenomenon observed in reactions in aqueous solution is discussed.

Calorimetry↗

PubMed1978

Thermodynamic studies of the interaction of alpha-chymotrypsin with water. I. Determination of the isosteric enthalpies and entropies of water binding to the native enzyme.

The enthalpies (deltaH) and entropies (deltaS) of the interaction of water with alpha-chymotrypsin were evaluated from multitemperature sorption isotherms in the temperature range 283--313 K, determined in a fully automatized, computer controlled sorption apparatus. The temperature dependence of deltaH and deltaS shows a marked anomaly in the temperature range 295--298 K. The experimental results are interpreted by a phase transition of the enzyme protein, and by the existence of a low- and high-temperature conformer of alpha-chymotrypsin below and above the transition region. The two conformers differ significantly in their water binding energetics, as proved by two F-tests based on analyses of variance. The deltaH and deltaS versus water content functions of the high and low temperature conformer show markedly different anomalies at and below 70 mol H2O per mol protein. This water content corresponds closely to the monolayer volume vm, (as defined by Brunauer, Emmett and Teller). The protein surface covered by one water-monolayer, agrees well with the polar and charged surface area of chymotrypsin, computed from X-ray data. The experimental results suggest that the interaction of the first water-monolayer with the protein surface induces major conformational changes. The energetic contributions of these structural changes dominate the deltaH and deltaS terms below vm, giving rise to the anomalies observed. Above this water content, their influence is drastically reduced, and the isosteric quantities are predominantly determined by the water binding process per se. This process is possibly related to the pronounced enthalphy-entropy compensation pattern exhibited by the deltaH and deltaS terms. A more detailed analysis and discussion of this compensation effect will be given.

Calorimetry↗

PubMed1975

Problems with entropy in biology.

Entropy has been widely referred to as a measure of biological order. The validity of this notion is discussed in conjunction with it's relation to the spontaneous creation of order. Information theory offers a quantitative method for characterization of order, however, it is not fundamentally connected to formalisms of irreversible thermodynamics, and it is severely limited because the meaning and value of the information is neglected. A completely general notation is proposed for including measures of order of a biological system in the entropy balance equation of irreversible thermodynamics. Problems of assigning energetic equivalents to measures of order are indicated, with a final focus on the problem of meaning and value.

Calorimetry↗

PubMed1976

Mechanoelectrical transduction in hyaluronic acid salt solution is an entropy-driven process.

An electrical potential develops between the ends of a column of hyaluronic salt solution displaced from a resting position by gentle pressure. A previous study demonstrated that such displacement changes the optical rotary dispersion properties of the salt, either increasing the rotation in the direction already shown by the salt before displacement or changing and increasing the rotation in the opposite direction, depending on the direction of the displacement. The present investigation demonstrates that the loss of bound water component across a membrane separating the solution and water is corelated with the extent of the column displacement. In addition, a return of the column to the position before displacement is correlated with a return of the water component across the membrane-but not at the same rate as the exodus. The data seem consistent with the hypothesis that the hyaluronic acid salt, when strained, adopts a less entropic configuration, releasing bound water and thus increasing the entropy of water component. This change in the distribution of entropy is reversible; i.e., Eddington's "time's arrow" is reversible with respect to the water component of the solution.

Female↗

PubMed1975

Phosphorylation of solubilized sarcoplasmic reticulum by orthophosphate and its thermodynamic characteristics. The dominant role of entropy in the phosphorylation.

A large fraction of the Ca-2plus- and Mg-2plus-dependent ATPase (EC 3.6.1.3) in sarcoplasmic reticulum membranes solubilized with Triton X-100 was phosphorylated with Pi. The phosphorylation required Mg-2plus but was strongly inhibited by low concentrations of Ca-2plus. A Ca-2plus ion concentration of 30 muM caused half-maximum inhibition in the presence of 50 mM MgCl2. The phosphorylated enzyme showed a rapid turnover and was in dynamic equilibrium with Pi in the medium. At equilibrium the amount of the phosphorylated enzyme increased markedly with increased in the reaction temperature. The apparent standard free energy change, the apparent standard enthalpy change, and the apparent standard entropy change in the formation of the phosphorylated enzyme from the enzyme-phosphate complex in the presence of excess Mg-2plus at 37 degrees and pH 7.0 were, respectively, 0.35 Cal per mol, 15.9 Cal per mol, and 50.2 e.u. per mol. The susceptibility of the acid-denatured phosphorylated enzyme to hydroxylamine showed that the phosphorylated enzyme is of an acyl phosphate type. The present results are consistent with the probability that the phosphorylation results from reversal of late steps in the Ca-2plus transport process. The results clearly show that the phosphorylated enzyme is stabilized by a great increase in entropy upon its formation from the enzyme-phosphate complex.

Adenosine Triphosphatases↗

PubMedDate not supplied

[Radiation entropy and its role in the process of photosynthesis].

The paper deals with the following problems: 1) radiation entropy and the value of maximum performance coefficient of photosynthesizing systems eta m; 2) problem of physical meaning of eta m and on its association with real processes in photosynthesis. It has been shown that for calculating entropy of nonequilibrium radiation its origin should be known and that the value eta m does not practically limit the processes which proceed in photosynthesis.

Mathematics↗