High impact information on Entropy

• Some partitioning processes, particularly involving polymeric solvents such as octanol or hexadecane, are governed not only by translational entropies and contact interactions, but also by free energies resulting from changes in the conformations of the polymer chains upon solute insertion [1].
• Enthalpies and entropies have been determined for the reversible binding of O2 and CO to chelated protoheme, a compound having a covalently attached imidazole bound to the iron [2].
• At 25 degrees the binding of NADPH and NADP+ is characterized by small negative enthalpies and large positive entropies whereas the binding of the folates and methotrexate is accompanied by large negative enthalpies and small negative entropies [3].
• Temperature effects on the catalytic activity of the D38E mutant of 3-oxo-Delta5-steroid isomerase: favorable enthalpies and entropies of activation relative to the nonenzymatic reaction catalyzed by acetate ion [4].
• Experimental differential entropies of hydration were found to be of the order of -20 cal/mol/K although values vary from system to system [5].

Biological context of Entropy

• The thermal inactivation of ISVPs approximated first-order kinetics over a range of temperatures, permitting the use of Arrhenius plots to estimate activation enthalpies and entropies that account for the different behaviors of T1L and T3D [6].
• Partition properties, that is partition coefficients and enthalpies (delta Hp degree) and entropies (delta Sp degree) of partition, have been measured for 50 benzoic acids in the 1-octanol/water system, and their role in QSAR (quantitative structure-activity relationship) analysis examined [7].
• Acceleration of either acetyl phosphate or ATP hydrolysis rates was promoted by a decrease in both activation energies (Ea) and in entropies of activation delta S [8].
• This article evaluates the differences in using heart rate versus heart period to estimate fractal dimensions and approximate entropies of these time series [9].

Anatomical context of Entropy

• The activation enthalpies and entropies for the association of actinomycin with deoxyguanosine 5'-monophosphate resemble closely those typical for calf thymus DNA [10].
• Adenylate cyclase in normal and transformed membranes differed in specific activity, V for ATP, activation entropies, sensitivity to Ca2+, and stability at 37 degrees C. Solubilization with Brij 96 abolished or greatly reduced these differences [11].

Associations of Entropy with chemical compounds

• Enthalpies and entropies for ferric ion binding were determined from calorimetric measurements [12].
• Activation enthalpies and entropies for the microscopic rate constants of acetate-catalyzed isomerization of 5-androstene-3,17-dione [13].
• Dissociation thresholds of 1.17 and 1.09 eV and activation entropies of -22.2 and -23.3 cal/(mol K) were obtained for des-Arg(1) and des-Arg(9)-bradykinin from RRKM modeling of time-resolved data [14].
• Azide and thiocyanate bind trans to a thiolate, and with similar entropies and enthalpies (thiocyanate: DeltaH = -7.5 +/- 1.1 kcal/mol, DeltaS = -17.2 +/- 3.2 eu; azide: DeltaH = -6.5 +/- 1.0 kcal/mol, DeltaS = -12.6 +/- 2.4 eu) [15].
• In addition, we assessed the "proline effect" on the conformational equilibria by comparing the differences in configurational entropies between the reverse turn and extended conformations of the two peptides [16].

Gene context of Entropy

• Thermodynamic coupling of cap-eIF4E association to intramolecular self-stacking of dinucleotide cap analogues strongly influences the enthalpies and entropies of the binding, but has a negligible effect on the resultant DeltaG degrees and DeltaC(p) degrees values [17].
• The spectral entropies show distinctly lower structural ordering for psiEst-6 than for Est-6 in all species studied [18].
• Using 3,3',4,4'-tetrachlorobiphenyl (TCB) as the reference compound, it is shown that PCBs having higher electron affinities, lower lipophilicities and entropies than TCB are potent ligands for rat hepatic AhR [19].
• The models show that lipophilicities, electron affinities, entropies and electronic energy gaps of PCBs are key physicochemical properties controlling their AhR, AHH and EROD activities [19].
• The relative enthalpies at 0 K and relative free energies at 298 K were based on the above-mentioned relative energies and zero-point vibration energies, temperature-dependent enthalpy terms and entropies evaluated at the MP2/6-31G level [20].

Analytical, diagnostic and therapeutic context of Entropy

• Differential scanning calorimetry (DSC) detected decreases of melting entropies (delta Sm) by the incorporation of cholesterol into both anhydrous and hydrated equimolar mixture of pseudo-ceramide (SLE) and stearic acid [21].
• Kulback-Leibler and renormalized entropies: applications to electroencephalograms of epilepsy patients [22].

References