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 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 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 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

scholarly journals Thermodynamics of DNA: heat capacity changes on duplex unfolding

2019 ◽  
Vol 48 (8) ◽  
pp. 773-779 ◽  
Author(s):  
Anatoliy Dragan ◽  
Peter Privalov ◽  
Colyn Crane-Robinson
Keyword(s):  
Heat Capacity ◽  
Accessible Surface Area ◽  
Solvent Accessible Surface Area ◽  
Polar Component ◽  
Heat Capacity Change ◽  
Dna Duplex ◽  
Capacity Change ◽  
Heat Capacity Changes ◽  
Accessible Surface ◽  
Lower Magnitude

Abstract The heat capacity change, ΔCp, accompanying the folding/unfolding of macromolecules reflects their changing state of hydration. Thermal denaturation of the DNA duplex is characterized by an increase in ΔCp but of much lower magnitude than observed for proteins. To understand this difference, the changes in solvent accessible surface area (ΔASA) have been determined for unfolding the B-form DNA duplex into disordered single strands. These showed that the polar component represents ~ 55% of the total increase in ASA, in contrast to globular proteins of similar molecular weight for which the polar component is only about 1/3rd of the total. As the exposure of polar surface results in a decrease of ΔCp, this explains the much reduced heat capacity increase observed for DNA and emphasizes the enhanced role of polar interactions in maintaining duplex structure. Appreciation of a non-zero ΔCp for DNA has important consequences for the calculation of duplex melting temperatures (Tm). A modified approach to Tm prediction is required and comparison is made of current methods with an alternative protocol.

Heat capacity change on isothermal vitrification during a macromolecule's growth

1993 ◽  
Vol 201 (1-3) ◽  
pp. 95-100 ◽  
Author(s):  
M. Cassettari ◽  
G. Salvetti ◽  
E. Tombari ◽  
S. Veronesi ◽  
G.P. Johari
Keyword(s):  
Heat Capacity ◽  
Heat Capacity Change ◽  
Capacity Change
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