scholarly journals Thermodynamics and Intermolecular Interactions of Nicotinamide in Neat and Binary Solutions: Experimental Measurements and COSMO-RS Concentration Dependent Reactions Investigations

2021 ◽  
Vol 22 (14) ◽  
pp. 7365
Author(s):  
Piotr Cysewski ◽  
Maciej Przybyłek ◽  
Anna Kowalska ◽  
Natalia Tymorek
Keyword(s):  
Intermolecular Interactions ◽  
Vibrational Energy ◽  
Perfect Match ◽  
Zero Point ◽  
Heat Capacity Change ◽  
Free Energies ◽  
Temperature Dependent ◽  
Scanning Calorimetry ◽  
Capacity Change ◽  
Self Association

In this study, the temperature-dependent solubility of nicotinamide (niacin) was measured in six neat solvents and five aqueous-organic binary mixtures (methanol, 1,4-dioxane, acetonitrile, DMSO and DMF). It was discovered that the selected set of organic solvents offer all sorts of solvent effects, including co-solvent, synergistic, and anti-solvent features, enabling flexible tuning of niacin solubility. In addition, differential scanning calorimetry was used to characterize the fusion thermodynamics of nicotinamide. In particular, the heat capacity change upon melting was measured. The experimental data were interpreted by means of COSMO-RS-DARE (conductor-like screening model for realistic solvation–dimerization, aggregation, and reaction extension) for concentration dependent reactions. The solute–solute and solute–solvent intermolecular interactions were found to be significant in all of the studied systems, which was proven by the computed mutual affinity of the components at the saturated conditions. The values of the Gibbs free energies of pair formation were derived at an advanced level of theory (MP2), including corrections for electron correlation and zero point vibrational energy (ZPE). In all of the studied systems the self-association of nicotinamide was found to be a predominant intermolecular complex, irrespective of the temperature and composition of the binary system. The application of the COSMO-RS-DARE approach led to a perfect match between the computed and measured solubility data, by optimizing the parameter of intermolecular interactions.

scholarly journals Stability of the Retinoid X Receptor-alpha Homodimer in the Presence and Absence of Rexinoid and Coactivator Peptide

2020 ◽  
Author(s):  
Zhengrong Yang ◽  
Donald D. Muccio ◽  
Nathalia Melo ◽  
Venkatram R. Atigadda ◽  
Matthew B. Renfrow
Keyword(s):  
Binding Pocket ◽  
Retinoid X Receptor ◽  
Heat Capacity Change ◽  
Scanning Calorimetry ◽  
Receptor Alpha ◽  
Average Value ◽  
A Value ◽  
Capacity Change ◽  
Differential Scanning Fluorimetry ◽  
Retinoid X Receptor Alpha

ABSTRACTDifferential scanning calorimetry and differential scanning fluorimetry were used to measure the thermal stability of human retinoid X receptor-alpha ligand binding domain (RXRα LBD) homodimer in the absence or presence of rexinoid and coactivator peptide, GRIP-1. The apo-RXRα LBD homodimer displayed a single thermal unfolding transition with a Tm of 58.7 °C and an unfolding enthalpy (ΔH) of 673 kJ/mol (12.5 J/g), much lower than average value (35 J/g) of small globular proteins. Using a heat capacity change (ΔCp) of 15 kJ/(mol·K) determined by measurements at different pH values, the free energy of unfolding (ΔG) of the native state was 33 kJ/mol at 37 °C. Rexinoid binding to the apo-homodimer increased Tm by 5 to 9 °C, and increased the ΔG of the native homodimer by 12 to 20 kJ/mol at 37 °C, consistent with the nanomolar dissociation constant (Kd) of the rexinoids. The increase in ΔG was the result of a more favorable entropic change due to interactions between the rexinoid and hydrophobic residues in the binding pocket, with the larger increases caused by rexinoids containing larger hydrophobic end groups. GRIP-1 binding to holo-homodimers containing rexinoid resulted in additional increases in ΔG of 14 kJ/mol, a value same for all three rexinoids. Binding of rexinoid and GRIP-1 resulted in a combined 50% increase in unfolding enthalpy, consistent with reduced structural fluidity and more compact folding observed in other published structural studies. Thermodynamic analysis thus provided a quantitative evaluation of the interactions between RXR and its agonist and coactivator.

scholarly journals Thermal and conformational stability of Ssh10b protein from archaeon Sulfolobus shibattae

2004 ◽  
Vol 382 (2) ◽  
pp. 433-440 ◽  
Author(s):  
Su XU ◽  
Sanbo QIN ◽  
Xian-Ming PAN
Keyword(s):  
Thermodynamic Parameters ◽  
Guanidine Hydrochloride ◽  
Conformational Stability ◽  
Structural Data ◽  
Heat Capacity Change ◽  
Temperature Dependent ◽  
Denatured State ◽  
Average Value ◽  
Capacity Change ◽  
True Values

The secondary structure of the DNA binding protein Ssh10b is largely unaffected by change in temperature between 25 °C and 85 °C, indicating that the protein is highly thermostable. Here, we report the temperature-dependent equilibrium denaturation of Ssh10b in the presence of guanidine hydrochloride (GdnHCl). It was found that the transition midpoint values of the temperature (Tm), and changes of enthalpy (ΔHm) and entropy (ΔSm) of Ssh10b unfolding were linearly decreasing with increasing GdnHCl concentration. The true values of the thermodynamic parameters, Tm=402 K, ΔHm=590±40 kJ·mol−1 and ΔSm=1.4±0.15 kJ·T−1·mol−1, were obtained by linear extrapolation to 0 M GdnHCl. The value of the heat capacity change of Ssh10b unfolding, ΔCp=3.8±0.2 kJ·T−1·mol−1 (approx. 19 J T−1·mol residue−1), was obtained from the measured thermodynamic parameters. This is significantly smaller than that of the average value for mesophilic proteins (50 J·K−1·mol residue−1) or the value calculated from the Ssh10b structural data (64 J T−1·mol residue−1). A consequence of the small ΔCp is that the ΔG of Ssh10b is larger than that of mesophilic proteins, while the values of ΔH and T*ΔS are smaller. The small ΔCp of Ssh10b appears to result mainly from the presence of compactness in the denatured state.

scholarly journals Raman Spectroscopy Studies on the Barocaloric Hybrid Perovskite [(CH3)4N][Cd(N3)3]

Molecules ◽  
2020 ◽  
Vol 25 (20) ◽  
pp. 4754
Author(s):  
Rosivaldo Xavier da Silva ◽  
Carlos William de Araujo Paschoal ◽  
Clenilton Costa dos Santos ◽  
Alberto García-Fernández ◽  
Jorge Salgado-Beceiro ◽  
...  
Keyword(s):  
Raman Spectroscopy ◽  
Phase Transitions ◽  
Intermolecular Interactions ◽  
Structural Phase ◽  
Blue Shift ◽  
Temperature Dependent ◽  
Scanning Calorimetry ◽  
Hybrid Perovskite ◽  
Entropy Variation ◽  
Spectroscopy Studies

Temperature-dependent Raman scattering and differential scanning calorimetry were applied to the study of the hybrid organic-inorganic azide-perovskite [(CH3)4N][Cd(N3)3], a compound with multiple structural phase transitions as a function of temperature. A significant entropy variation was observed associated to such phase transitions, |∆S| ~ 62.09 J·kg−1 K−1, together with both a positive high barocaloric (BC) coefficient |δTt/δP| ~ 12.39 K kbar−1 and an inverse barocaloric (BC) coefficient |δTt/δP| ~ −6.52 kbar−1, features that render this compound interesting for barocaloric applications. As for the obtained Raman spectra, they revealed that molecular vibrations associated to the NC4, N3– and CH3 molecular groups exhibit clear anomalies during the phase transitions, which include splits and discontinuity in the phonon wavenumber and lifetime. Furthermore, variation of the TMA+ and N3– modes with temperature revealed that while some modes follow the conventional red shift upon heating, others exhibit an unconventional blue shift, a result which was related to the weakening of the intermolecular interactions between the TMA (tetramethylammonium) cations and the azide ligands and the concomitant strengthening of the intramolecular bondings. Therefore, these studies show that Raman spectroscopy is a powerful tool to gain information about phase transitions, structures and intermolecular interactions between the A-cation and the framework, even in complex hybrid organic-inorganic perovskites with highly disordered phases.

scholarly journals Heat capacity change for ribonuclease A folding

1999 ◽  
Vol 8 (7) ◽  
pp. 1500-1504 ◽  
Author(s):  
C. Nick Pace ◽  
Gerald R. Grimsley ◽  
Susan T. Thomas ◽  
George I. Makhatadze
Keyword(s):  
Heat Capacity ◽  
Ribonuclease A ◽  
Heat Capacity Change ◽  
Capacity Change

scholarly journals Structural elastic and thermal properties of SrxCd1−x O mixed compounds — a theoretical approach

2014 ◽  
Vol 32 (3) ◽  
pp. 350-357
Author(s):  
Purvee Bhardwaj
Keyword(s):  
Phase Transition ◽  
Vibrational Energy ◽  
Zero Point ◽  
Study Phase ◽  
Energy Effect ◽  
Phase Transition Pressure ◽  
Vegard’S Law ◽  
Extended Interaction ◽  
Experimental Values ◽  
Good Agreement

AbstractIn the present paper, the structural and mechanical properties of alkaline earth oxides mixed compound SrxCd1−x O (0 ≤ x ≤ 1) under high pressure have been reported. An extended interaction potential (EIP) model, including the zero point vibrational energy effect, has been developed for this study. Phase transition pressures are associated with a sudden collapse in volume. Phase transition pressure and associated volume collapses [ΔV (Pt)/V(0)] calculated from this approach are in good agreement with the experimental values for the parent compounds (x = 0 and x = 1). The results for the mixed crystal counterparts are also in fair agreement with experimental data generated from the application of Vegard’s law to the data for the parent compounds.

scholarly journals Temperature control technology by heat capacity change upon lock and key binding

2010 ◽  
Vol 375 (2) ◽  
pp. 165-169 ◽  
Author(s):  
Ken-ichi Amano ◽  
Daisuke Miyazaki ◽  
Liew Fong Fong ◽  
Paul Hilscher ◽  
Taro Sonobe
Keyword(s):  
Heat Capacity ◽  
Temperature Control ◽  
Heat Capacity Change ◽  
Control Technology ◽  
Capacity Change

Morphological basis for the complex melting behaviour of isotactic polystyrene

e-Polymers ◽  
2002 ◽  
Vol 2 (1) ◽  
Author(s):  
Mahmoud Al-Hussein ◽  
Gert Strobl
Keyword(s):  
Morphological Changes ◽  
Melting Behaviour ◽  
Temperature Dependent ◽  
Molten Material ◽  
Scanning Calorimetry ◽  
Isotactic Polystyrene ◽  
X Ray ◽  
Long Period ◽  
X Ray Scattering ◽  
Increasing Temperature

AbstractTemperature-dependent small-angle X-ray scattering spectroscopy of isothermally cold crystallized isotactic polystyrene revealed considerable morphological reorganization during subsequent heating to the melt. Both the crystalline thickness and the long period increased continuously with increasing temperature before the samples finally melted. The temperature dependence of these changes correlated very well with the melting behaviour observed with differential scanning calorimetry. As the temperature increased during a heating scan, the initial lamellae that formed during isothermal crystallization showed only little reorganization until they started to melt. Then, the molten material recrystallized continuously into increasingly thicker lamellae at increasing temperature until they finally melted. As the crystallization temperature approached the final melting temperature of the recrystallized lamellae, the initial lamellae melted without further recrystallization and no morphological changes were seen in this case.

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