Effects of estradiol and 4-hydroxytamoxifen on the conformation, thermal stability, and DNA recognition of estrogen receptor β

2007 ◽  
Vol 85 (1) ◽  
pp. 1-10 ◽  
Author(s):  
Veena Vijayanathan ◽  
Norma J. Greenfield ◽  
T. J. Thomas ◽  
Margarita M. Ivanova ◽  
Valentyn V. Tyulmenkov ◽  
...  
Keyword(s):  
Thermal Stability ◽  
Binding Affinity ◽  
Dna Recognition ◽  
Thermal Unfolding ◽  
Estrogen Response Element ◽  
Cd Spectrum ◽  
Estrogen Response ◽  
Helical Content ◽  
Partial Unfolding ◽  
Thermal Stability Of

Estrogen receptors (ERα and ERβ) are ligand-activated transcription factors. We examined the effects of estradiol (E2), 4-hydroxytamoxifen (HT), and the estrogen response element (ERE) on the helical content and thermal unfolding of ERβ. A circular dichroism (CD) spectrum of ERβ showed changes at 210 and 222 nm that were due to the presence of E2, which is indicative of partial unfolding. In contrast, HT did not alter the CD spectrum of ERβ. The addition of E2 + ERE caused an increase in the α-helical content and an increase in the temperature midpoint of folding transition (TM) from 39 ± 0.7 °C to 57.2 ± 1 °C. The addition of E2 + mutant ERE, or E2 + control oligonucleotide, increased the TM of ERβ to 45 ± 2 °C only. In the presence of HT, ERβ yielded similar TM values (55–58 °C) with ERE, mutant ERE, or control oligodeoxynucleotide. The binding affinity of ERβ for ERE increased 125.7-fold as a result of the presence of E2, but only 4-fold as a result of HT. These results demonstrate coupled effects of E2 and ERE on ERβ stability and binding affinity. The increased thermal stability of HT–ERβ–ERE was associated with reduced specificity of ERβ–ERE recognition, illustrating profound differences in conformational states of ERβ induced by E2 and HT.

scholarly journals Antigen-binding affinity and thermostability of chimeric mouse-chicken IgY and mouse-human IgG antibodies with identical variable domains

2019 ◽  
Vol 9 (1) ◽  
Author(s):  
Juho Choi ◽  
Minjae Kim ◽  
Joungmin Lee ◽  
Youngsil Seo ◽  
Yeonkyoung Ham ◽  
...  
Keyword(s):  
Thermal Stability ◽  
Binding Affinity ◽  
Antigen Binding ◽  
Chimeric Mouse ◽  
Binding Parameters ◽  
Igg Antibodies ◽  
Human Igg ◽  
Variable Domains ◽  
Thermal Stability Of ◽  
Parental Mouse

AbstractConstant (C)-region switching of heavy (H) and/or light (L) chains in antibodies (Abs) can affect their affinity and specificity, as demonstrated using mouse, human, and chimeric mouse-human (MH) Abs. However, the consequences of C-region switching between evolutionarily distinct mammalian and avian Abs remain unknown. To explore C-region switching in mouse-chicken (MC) Abs, we investigated antigen-binding parameters and thermal stability of chimeric MC-6C407 and MC-3D8 IgY Abs compared with parental mouse IgGs and chimeric MH Abs (MH-6C407 IgG and MH-3D8 IgG) bearing identical corresponding variable (V) regions. The two MC-IgYs exhibited differences in antigen-binding parameters and thermal stability from their parental mouse Abs. However, changes were similar to or less than those between chimeric MH Abs and their parental mouse Abs. The results demonstrate that mammalian and avian Abs share compatible V-C region interfaces, which may be conducive for the design and utilization of mammalian-avian chimeric Abs.

scholarly journals Effect of tartaric acid on conformation and stability of human prostatic phosphatase: an infrared spectroscopic and calorimetric study.

2001 ◽  
Vol 48 (3) ◽  
pp. 755-762 ◽  
Author(s):  
S Bem ◽  
W S Ostrowski
Keyword(s):  
Thermal Stability ◽  
Differential Scanning Calorimetry ◽  
Fourier Transform ◽  
Tartaric Acid ◽  
Solution Structure ◽  
Prostatic Acid Phosphatase ◽  
Thermal Unfolding ◽  
Calorimetric Study ◽  
Scanning Calorimetry ◽  
Thermal Stability Of

The solution structure and thermal stability of human prostatic acid phosphatase (hPAP) in the absence and in the presence of tartaric acid were studied by Fourier transform infrared spectroscopy (FTIR) and differential scanning calorimetry (DSC). The temperature dependence of the infrared spectrum and DSC scans indicate that hPAP undergoes thermal unfolding at a temperature between 49.5 and 52.5 degrees C. Binding of tartaric acid does not lead to major changes in the secondary structure of hPAP, however, hPAP with bound tartaric acid shows a significantly increased thermal stability. These results helped to better understand the mechanism of hPAP unfolding at the elevated temperature.

scholarly journals Experimental Insight into the Structural and Functional Roles of the ‘Black’ and ‘Gray’ Clusters in Recoverin, a Calcium Binding Protein with Four EF-Hand Motifs

Molecules ◽  
2019 ◽  
Vol 24 (13) ◽  
pp. 2494
Author(s):  
Sergey E. Permyakov ◽  
Alisa S. Vologzhannikova ◽  
Ekaterina L. Nemashkalova ◽  
Alexei S. Kazakov ◽  
Alexander I. Denesyuk ◽  
...  
Keyword(s):  
Thermal Stability ◽  
Amino Acids ◽  
Calcium Binding ◽  
Binding Protein ◽  
Critical Role ◽  
Binding Motif ◽  
Terminal Domain ◽  
Ef Hand ◽  
Helical Content ◽  
Thermal Stability Of

Recently, we have found that calcium binding proteins of the EF-hand superfamily (i.e., a large family of proteins containing helix-loop-helix calcium binding motif or EF-hand) contain two types of conserved clusters called cluster I (‘black’ cluster) and cluster II (‘grey’ cluster), which provide a supporting scaffold for the Ca2+ binding loops and contribute to the hydrophobic core of the EF-hand domains. Cluster I is more conservative and mostly incorporates aromatic amino acids, whereas cluster II includes a mix of aromatic, hydrophobic, and polar amino acids of different sizes. Recoverin is EF-hand Ca2+-binding protein containing two ‘black’ clusters comprised of F35, F83, Y86 (N-terminal domain) and F106, E169, F172 (C-terminal domain) as well as two ‘gray’ clusters comprised of F70, Q46, F49 (N-terminal domain) and W156, K119, V122 (C-terminal domain). To understand a role of these residues in structure and function of human recoverin, we sequentially substituted them for alanine and studied the resulting mutants by a set of biophysical methods. Under metal-free conditions, the ‘black’ clusters mutants (except for F35A and E169A) were characterized by an increase in the α-helical content, whereas the ‘gray’ cluster mutants (except for K119A) exhibited the opposite behavior. By contrast, in Ca2+-loaded mutants the α-helical content was always elevated. In the absence of calcium, the substitutions only slightly affected multimerization of recoverin regardless of their localization (except for K119A). Meanwhile, in the presence of calcium mutations in N-terminal domain of the protein significantly suppressed this process, indicating that surface properties of Ca2+-bound recoverin are highly affected by N-terminal cluster residues. The substitutions in C-terminal clusters generally reduced thermal stability of recoverin with F172A (‘black’ cluster) as well as W156A and K119A (‘gray’ cluster) being the most efficacious in this respect. In contrast, the mutations in the N-terminal clusters caused less pronounced differently directed changes in thermal stability of the protein. The substitutions of F172, W156, and K119 in C-terminal domain of recoverin together with substitution of Q46 in its N-terminal domain provoked significant but diverse changes in free energy associated with Ca2+ binding to the protein: the mutant K119A demonstrated significantly improved calcium binding, whereas F172A and W156A showed decrease in the calcium affinity and Q46A exhibited no ion coordination in one of the Ca2+-binding sites. The most of the N-terminal clusters mutations suppressed membrane binding of recoverin and its inhibitory activity towards rhodopsin kinase (GRK1). Surprisingly, the mutant W156A aberrantly activated rhodopsin phosphorylation regardless of the presence of calcium. Taken together, these data confirm the scaffolding function of several cluster-forming residues and point to their critical role in supporting physiological activity of recoverin.

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

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