Effect of osmolytes on the thermal stability of proteins: replica exchange simulations of Trp-cage in urea and betaine solutions

2018 ◽  
Vol 20 (16) ◽  
pp. 11174-11182 ◽  
Author(s):  
Beata Adamczak ◽  
Mateusz Kogut ◽  
Jacek Czub
Keyword(s):  
Thermal Stability ◽  
Molecular Mechanism ◽  
Thermal Denaturation ◽  
Replica Exchange ◽  
Thermal Stability Of ◽  
Denaturation Of Proteins

Although osmolytes are known to modulate the folding equilibrium, the molecular mechanism of their effect on thermal denaturation of proteins is still poorly understood.

scholarly journals Application of Glycation in Regulating the Heat-Induced Nanoparticles of Egg White Protein

Nanomaterials ◽  
2018 ◽  
Vol 8 (11) ◽  
pp. 943 ◽  
Author(s):  
Chenying Wang ◽  
Xidong Ren ◽  
Yujie Su ◽  
Yanjun Yang
Keyword(s):  
Thermal Stability ◽  
Protein Concentration ◽  
Thermal Denaturation ◽  
Negative Charge ◽  
Activity Index ◽  
Stability Index ◽  
Egg White ◽  
Egg White Protein ◽  
Neutral Conditions ◽  
Thermal Stability Of

Due to the poor thermal stability of egg white protein (EWP), important challenges remain regarding preparation of nanoparticles for EWP above the denaturation temperature at neutral conditions. In this study, nanoparticles were fabricated from conjugates of EWP and isomalto-oligosaccharide (IMO) after heating at 90 °C for 30 min. Meanwhile, the effects of protein concentration, temperature, pH, ionic strength and degree of glycation (DG) on the formation of nanoparticles from IMO-EWP were investigated. To further reveal the formation mechanism of the nanoparticles, structures, thermal denaturation properties and surface properties were compared between EWP and IMO-EWP conjugates. Furthermore, the emulsifying activity index (EAI) and the emulsifying stability index (ESI) of nanoparticles were determined. The results indicated that glycation enhanced thermal stability and net surface charge of EWP due to changes in the EWP structure. The thermal aggregation of EWP was inhibited significantly by glycation, and enhanced with a higher degree of glycation. Meanwhile, the nanoparticles (<200 nm in size) were obtained at pH 3.0, 7.0 and 9.0 in the presence of NaCl. The increased thermal stability and surface net negative charge after glycation contributed to the inhibition. The EAI and ESI of nanoparticles were increased nearly 3-fold and 2-fold respectively, as compared to unheated EWP.

scholarly journals THE THERMAL STABILITY OF RHODOPSIN AND OPSIN

1958 ◽  
Vol 42 (2) ◽  
pp. 259-280 ◽  
Author(s):  
Ruth Hubbard
Keyword(s):  
Thermal Stability ◽  
Thermal Denaturation ◽  
Species Differences ◽  
Activation Energies ◽  
Specific Relationship ◽  
Thermal Bleaching ◽  
Thermal Stability Of ◽  
Cis Isomer

Rhodopsin, the red photosensitive pigment of rod vision, is composed of a specific cis isomer of retinene, neo-b (11-cis), joined as chromophore to a colorless protein, opsin. We have investigated the thermal denaturation of cattle rhodopsin and opsin in aqueous digitonin solution, and in isolated rod outer limbs. Both rhodopsin and opsin are more stable in rods than in solution. In solution as well as in rods, moreover, rhodopsin is considerably more stable than opsin. The chromophore therefore protects opsin against denaturation. This is true whether rhodopsin is extracted from dark-adapted retinas, or synthesized in vitro from neo-b retinene and opsin. Excess neo-b retinene does not protect rhodopsin against denaturation. The protection involves the specific relationship between the chromophore and opsin. Similar, though somewhat less, protection is afforded opsin by the stereoisomeric iso-a (9-cis) chromophore in isorhodopsin. The Arrhenius activation energies (Ea) and entropies of activation (ΔS‡) are much greater for thermal denaturation of rhodopsin and isorhodopsin than of opsin. Furthermore, these values differ considerably for rhodopsins from different species —frog, squid, cattle—presumably due to species differences in the opsins. Heat or light bleaches rhodopsin by different mechanisms, yielding different products. Light stereoisomerizes the retinene chromophore; heat denatures the opsin. Photochemical bleaching therefore yields all-trans retinene and native opsin; thermal bleaching, neo-b retinene and denatured opsin.

An unusual effect of NADP+ on the thermostability of the nonphosphorylating glyceraldehyde-3-phosphate dehydrogenase from Streptococcus mutans

2013 ◽  
Vol 91 (5) ◽  
pp. 295-302 ◽  
Author(s):  
Denis Arutyunov ◽  
Elena Schmalhausen ◽  
Victor Orlov ◽  
Sophie Rahuel-Clermont ◽  
Natalia Nagradova ◽  
...  
Keyword(s):  
Thermal Stability ◽  
Streptococcus Mutans ◽  
Thermal Denaturation ◽  
Thermal Inactivation ◽  
Protein Molecule ◽  
Single Amino Acid ◽  
Binary Complex ◽  
Scanning Calorimetry ◽  
Active Centre ◽  
Thermal Stability Of

Adiabatic differential scanning calorimetry was used to investigate the effect of NADP+ on the irreversible thermal denaturation of the nonphosphorylating glyceraldehyde-3-phosphate dehydrogenase (GAPN) from Streptococcus mutans. The GAPN–NADP+ binary complex showed a strongly decreased thermal stability, with a difference of about 20 °C between the temperatures of the thermal transition peak maxima of the complex and the free protein. This finding was similar to the previously described thermal destabilization of GAPN upon binding of inorganic phosphate to the substrate binding site and can be interpreted as the shift of the equilibrium between 2 conformers of tetrameric GAPN upon addition of the coenzyme. Single amino acid substitution, known to abolish the NADP+ binding, cancelled the calorimetric effect of the coenzyme. GAPN thermal inactivation was considerably decelerated in the presence of NADP+ showing that the apparent change in stability of the active centre can be the opposite to that of the whole protein molecule. NADP+ could also reactivate the inactive GAPN* species, obtained by the heating of the apoenzyme below the thermal denaturation transition temperature. These effects may reflect a mechanism that provides GAPN the sufficient flexibility for the earlier observed profound active site reorganizations required during the catalytic cycle. The elevated thermal stability of the apoenzyme may, in turn, be important for maintaining a constant level of active GAPN — an enzyme that is known to be crucial for the effective supply of the reducing equivalents in S. mutans and its ability to grow under aerobic conditions.

Influence of complex formation with tetraantraquinoporphyrazines and tetrasulphophthalocyanine on thermal stability of bovine serum albumin

2011 ◽  
Vol 15 (04) ◽  
pp. 223-229 ◽  
Author(s):  
Natalia Lebedeva ◽  
Tatyana Popova ◽  
Malgorzata Kozbial ◽  
Malgorzata Wszelaka-Rylik ◽  
Yuri Gubarev ◽  
...  
Keyword(s):  
Thermal Stability ◽  
Differential Scanning Calorimetry ◽  
Bovine Serum Albumin ◽  
Complex Formation ◽  
Serum Albumin ◽  
Bovine Serum ◽  
Thermal Denaturation ◽  
Scanning Calorimetry ◽  
Electron Absorption Spectroscopy ◽  
Thermal Stability Of

Interaction between bovine serum albumin (BSA) and tetraantraquinoporphyrazines (TAP) and tetrasulphophthalocyanine (Pc) aluminum hydroxide was studied by means of electron absorption spectroscopy, IR spectroscopy, fluorescence spectroscopy and differential scanning calorimetry. It was found that the complex formation of BSA with the TAPs results in increase of thermal stability of the protein while Pc does not have remarkable influence on the protein thermal denaturation.

scholarly journals Interaction of D-600 with the transmembrane domain of the sarcoplasmic reticulum Ca2+-ATPase

2000 ◽  
Vol 279 (1) ◽  
pp. C166-C172 ◽  
Author(s):  
Alicia Ortega ◽  
V. M. Becker ◽  
R. Alvarez ◽  
J. R. Lepock ◽  
H. Gonzalez-Serratos
Keyword(s):  
Thermal Stability ◽  
Sarcoplasmic Reticulum ◽  
Atpase Activity ◽  
Thermal Denaturation ◽  
Thermal Inactivation ◽  
Channel Blocker ◽  
Transmembrane Domain ◽  
Muscle Cells ◽  
The Stability ◽  
Thermal Stability Of

Experiments were performed to determine whether the organic Ca2+ channel blocker D-600 (gallopamil), which penetrates into muscle cells, affects sarcoplasmic reticulum (SR) Ca2+ uptake by directly inhibiting the light SR Ca2+-ATPase. We have previously shown that at 10 μM, D-600 inhibits LSR ATP-dependent Ca2+ uptake by 50% but has no effect on ATPase activity (21). These data suggest that the SR Ca2+-ATPase might be a potential target for D-600. The ATPase activity of the enzyme is associated with its hydrophilic cytoplasmic domain, whereas Ca2+ binding and translocation are associated with the transmembrane domain (18). In the present experiments, we determined which of the two domains of the ATPase is affected by D-600. Thermal inactivation experiments using the SR Ca2+-ATPase demonstrated that D-600 decreased the thermal stability of Ca2+ transport but had no effect on the stability of ATPase activity. In addition, D-600 at a concentration of 160 μM did not have any leaking effect of Ca2+ on the Ca2+-loaded SR. Thermal denaturation profiles of SR membranes revealed that D-600 interacts directly with the transmembrane domain of the Ca2+-ATPase. No evidence for interaction with the nucleotide domain was obtained. We conclude that the Ca2+ blocker D-600 inhibits the SR Ca2+ pump specifically by interacting with the transmembrane Ca2+-binding domain of the Ca2+-ATPase.

Catalytic activity and thermal stability of horseradish peroxidase encapsulated in self-assembled organic nanotubes

The Analyst ◽  
2016 ◽  
Vol 141 (7) ◽  
pp. 2191-2198 ◽  
Author(s):  
Qin Lu ◽  
Youngchan Kim ◽  
Nabil Bassim ◽  
Nisha Raman ◽  
Greg E. Collins
Keyword(s):  
Thermal Stability ◽  
Catalytic Activity ◽  
Elevated Temperature ◽  
Horseradish Peroxidase ◽  
Thermal Denaturation ◽  
Self Assembled ◽  
Temperature Exposure ◽  
Organic Nanotubes ◽  
Thermal Stability Of

The confined nanospace of organic nanotubes protects enzymes against thermal denaturation and preserves catalytic activity following prolonged elevated temperature exposure.

The Ordered Phase Formation in Ti-Al-Ga Alloys

1970 ◽  
Vol 28 ◽  
pp. 440-441
Author(s):  
Shiro Fujishiro ◽  
Harold L. Gegel
Keyword(s):  
Thermal Stability ◽  
High Temperature ◽  
Titanium Alloys ◽  
Growth Kinetics ◽  
Stoichiometric Composition ◽  
Good Potential ◽  
Alpha Titanium ◽  
Cold Rolled ◽  
Kinetics Of ◽  
Thermal Stability Of

Ordered-alpha titanium alloys having a DO19 type structure have good potential for high temperature (600°C) applications, due to the thermal stability of the ordered phase and the inherent resistance to recrystallization of these alloys. Five different Ti-Al-Ga alloys consisting of equal atomic percents of aluminum and gallium solute additions up to the stoichiometric composition, Ti3(Al, Ga), were used to study the growth kinetics of the ordered phase and the nature of its interface.The alloys were homogenized in the beta region in a vacuum of about 5×10-7 torr, furnace cooled; reheated in air to 50°C below the alpha transus for hot working. The alloys were subsequently acid cleaned, annealed in vacuo, and cold rolled to about. 050 inch prior to additional homogenization

Microstructure studies of tungsten silicide schottky contacts on Gaas

1987 ◽  
Vol 45 ◽  
pp. 328-329
Author(s):  
Yih-Cheng Shih ◽  
E. L. Wilkie
Keyword(s):  
Thermal Stability ◽  
Field Effect Transistors ◽  
Schottky Contact ◽  
Schottky Contacts ◽  
Excellent Thermal Stability ◽  
Barrier Heights ◽  
Gaas Substrates ◽  
Film Adhesion ◽  
Threshold Voltages ◽  
Thermal Stability Of

Tungsten silicides (WSix) have been successfully used as the gate materials in self-aligned GaAs metal-semiconductor-field- effect transistors (MESFET). Thermal stability of the WSix/GaAs Schottky contact is of major concern since the n+ implanted source/drain regions must be annealed at high temperatures (∼ 800°C). WSi0.6 was considered the best composition to achieve good device performance due to its low stress and excellent thermal stability of the WSix/GaAs interface. The film adhesion and the uniformity in barrier heights and ideality factors of the WSi0.6 films have been improved by depositing a thin layer of pure W as the first layer on GaAs prior to WSi0.6 deposition. Recently WSi0.1 has been used successfully as the gate material in 1x10 μm GaAs FET's on the GaAs substrates which were sputter-cleaned prior to deposition. These GaAs FET's exhibited uniform threshold voltages across a 51 mm wafer with good film adhesion after annealing at 800°C for 10 min.

Thermal stability of Al-Cu-Fe icosahedral alloys

1991 ◽  
Vol 1 (12) ◽  
pp. 1823-1836 ◽  
Author(s):  
M. Bessière ◽  
A. Quivy ◽  
S. Lefebvre ◽  
J. Devaud-Rzepski ◽  
Y. Calvayrac
Keyword(s):  
Thermal Stability ◽  
Thermal Stability Of
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