scholarly journals 670. Probing the Stability of rAAV Capsids and Genomic Constructs Using Differential Scanning Calorimetry in Concert With Mobile Phase Modifiers

2015 ◽  
Vol 23 ◽  
pp. S267
Author(s):  
James D. Maratt ◽  
Samantha F. Povlich ◽  
Christopher J. Morrison ◽  
Gwendolyn M. Wilmes ◽  
Samuel C. Wadsworth ◽  
...  
Keyword(s):  
Differential Scanning Calorimetry ◽  
Mobile Phase ◽  
Scanning Calorimetry ◽  
Mobile Phase Modifiers ◽  
The Stability

Thermotoga neapolitana Homotetrameric Xylose Isomerase Is Expressed as a Catalytically Active and Thermostable Dimer in Escherichia coli

1998 ◽  
Vol 64 (7) ◽  
pp. 2357-2360 ◽  
Author(s):  
J. Michael Hess ◽  
Vladimir Tchernajenko ◽  
Claire Vieille ◽  
J. Gregory Zeikus ◽  
Robert M. Kelly
Keyword(s):  
Escherichia Coli ◽  
Differential Scanning Calorimetry ◽  
Gel Filtration ◽  
Xylose Isomerase ◽  
Thermotoga Neapolitana ◽  
Thermal Transitions ◽  
Scanning Calorimetry ◽  
Catalytically Active ◽  
The Stability ◽  
Tetrameric Form

ABSTRACT The xylA gene from Thermotoga neapolitana5068 was expressed in Escherichia coli. Gel filtration chromatography showed that the recombinant enzyme was both a homodimer and a homotetramer, with the dimer being the more abundant form. The purified native enzyme, however, has been shown to be exclusively tetrameric. The two enzyme forms had comparable stabilities when they were thermoinactivated at 95°C. Differential scanning calorimetry revealed thermal transitions at 99 and 109.5°C for both forms, with an additional shoulder at 91°C for the tetramer. These results suggest that the association of the subunits into the tetrameric form may have little impact on the stability and biocatalytic properties of the enzyme.

Studies on the stability of creatine kinase isozymes

2003 ◽  
Vol 81 (1) ◽  
pp. 9-16 ◽  
Author(s):  
Zhi Guo ◽  
Zheng Wang ◽  
Xicheng Wang
Keyword(s):  
Differential Scanning Calorimetry ◽  
Creatine Kinase ◽  
Freeze Drying ◽  
Biological Significance ◽  
Subunit Interactions ◽  
Scanning Calorimetry ◽  
Gradient Gel Electrophoresis ◽  
The Stability ◽  
Creatine Kinase Isozymes ◽  
Monomer Form

Research on the stabilizing properties of creatine kinase isozymes CK-BB, CK-MB, and CK-MM showed that minor alteration of their sequence and structure influenced their stability significantly. An analysis of the stability of the isozymes in storage after freeze drying indicates that creatine kinase isozymes are all in monomer form because of the loss of subunit interactions. Freeze-drying leads to the oxidization of CK-BB and rearrangement of CK-MB. There are also differences in the unfolding of the isozymes in urea. CK-BB and CK-MB are unfolded in lower urea concentrations than CK-MM. Differences in the thermal unfolding were also examined by differential scanning calorimetry. This paper discusses the potential biological significance of these results.Key words: creatine kinase isozymes, fluorescence, circular dichroism, differential scanning calorimetry, urea gradient gel electrophoresis.

Structural Relaxation and Crystallization in a Pd40Cu30Ni10P20 Bulk Metallic Glass

2003 ◽  
Vol 806 ◽  
Author(s):  
R. Raghavan ◽  
U. Ramamurty ◽  
J. Basu ◽  
S. Ranganathan ◽  
N. Nishiyama
Keyword(s):  
Differential Scanning Calorimetry ◽  
Glass Transition ◽  
Metallic Glass ◽  
Bulk Metallic Glass ◽  
Structural Relaxation ◽  
Short Range ◽  
Annealing Temperature ◽  
Scanning Calorimetry ◽  
Short Range Ordering ◽  
The Stability

ABSTRACTThe stability of a Pd40Cu30Ni10P20 bulk metallic glass (BMG) against structural relaxation is investigated by isothermal and isochronal annealing heat treatments below and above its glass transition temperature, Tg, for varying periods. Differential scanning calorimetry (DSC) of the annealed samples shows an excess endotherm at Tg, irrespective of the annealing temperature. This recovery peak evolves exponentially with annealing time and is due to the destruction of anneal-induced compositional short range ordering. The alloy exhibits a high resistance to crystallization on annealing below Tg and complex Pd- and Ni-phosphides evolve on annealing above Tg.

Studies of Elastomer Oxidation via Thermal Analysis

1999 ◽  
Vol 72 (1) ◽  
pp. 165-173 ◽  
Author(s):  
D. J. Burlett
Keyword(s):  
Thermal Analysis ◽  
Differential Scanning Calorimetry ◽  
Oxidation Process ◽  
Industrial Applications ◽  
Scanning Calorimetry ◽  
Thermoanalytical Techniques ◽  
The Stability ◽  
Induction Times ◽  
Oxidation Susceptibility

Abstract Elastomers are used in many industrial applications because of their remarkable toughness and elasticity. However, the source of these properties is also a weakness, in that loss of properties via oxidation is an important factor in their selection. Thermoanalytical techniques, such as differential scanning calorimetry (DSC), provide useful tools for the characterization of the stability of elastomers. DSC can not only be used to determine oxidative induction times under isothermal conditions but can also be used to determine apparent overall activation energies of the oxidation process. An evaluation of these techniques is made and the technique is used to compare the oxidation susceptibility of polybutadienes of different microstructure. The results of these DSC scans are interpreted in terms of the chemistry of the oxidation process using FTIR results.

Evaluation of the stability of some alloys in the Cu–As–Te glassy system by differential scanning calorimetry

1998 ◽  
Vol 35 (3-4) ◽  
pp. 151-156 ◽  
Author(s):  
J Vázquez ◽  
P.L López-Alemany ◽  
P Villares ◽  
R Jiménez-Garay
Keyword(s):  
Differential Scanning Calorimetry ◽  
Glassy System ◽  
Scanning Calorimetry ◽  
The Stability

scholarly journals A simultaneous X-ray diffraction–differential scanning calorimetry study into the phase transitions of mefenamic acid

2019 ◽  
Vol 52 (6) ◽  
pp. 1264-1270 ◽  
Author(s):  
Yuying Pang ◽  
Asma Buanz ◽  
Richard Telford ◽  
Oxana V. Magdysyuk ◽  
Simon Gaisford ◽  
...  
Keyword(s):  
Differential Scanning Calorimetry ◽  
Mefenamic Acid ◽  
Cell Expansion ◽  
X Ray Diffraction ◽  
Scanning Calorimetry ◽  
Differential Scanning Calorimetry Study ◽  
Polymorphic Transitions ◽  
X Ray ◽  
New Form ◽  
The Stability

In this study, the polymorphic transitions of mefenamic acid (MA) were studied by synchrotron X-ray powder diffraction combined with differential scanning calorimetry (XRD-DSC). The initial material was found to be phase-pure form I which, when heated, produces two endotherms that can be observed by DSC at 162.72 and 219.55°C. The former was found to correspond to a solid–solid enantiotropic transition from form I to a mixture of forms II and III. The latter is the melting point of form II. As form I is heated, significantly greater unit-cell expansion is seen in the a direction than in b and c, which can be explained by the stronger intermolecular interactions in the bc plane. Refinements of the reported MA structures against the patterns collected during heating revealed that at 175°C there exists a mixture of forms I, II and III, whereas only forms II and III remain at 205°C. However, reflections are observed at both temperatures which cannot be fitted with the known forms of MA. It is hypothesized that a new form of MA is produced upon heating. The stability of MA after the enantiotropic transition temperature is II > III > I, which differs from the previously reported II > I > III.

scholarly journals Enthalpies of Combustion and Formation of Histidine Stereoisomers

2018 ◽  
Vol 2018 ◽  
pp. 1-6
Author(s):  
A. Neacsu ◽  
D. Gheorghe ◽  
I. Contineanu ◽  
A. M. Sofronia ◽  
F. Teodorescu ◽  
...  
Keyword(s):  
Differential Scanning Calorimetry ◽  
Crystalline State ◽  
Enthalpies Of Formation ◽  
Racemic Mixture ◽  
Group Additivity ◽  
Scanning Calorimetry ◽  
Combustion Energy ◽  
Temperature Range ◽  
Decomposition Reactions ◽  
The Stability

The combustion energy of histidine enantiomers (L and D) and of their racemic mixture was measured experimentally. The following values for the enthalpies of formation corresponding to the crystalline state were derived (L = −451.7, D = −448.7, DL = −451.5 kJ·mol−1), and information concerning their stability was obtained by correlating the values of the above thermochemical quantity with the structure of the molecules by using the group additivity scheme. The samples were characterized using a simultaneous thermogravimetry (TG) coupled with differential scanning calorimetry (DSC) techniques in the temperature range between ambient and beyond melting-decomposition, and the corresponding parameters were calculated. The high values of the decomposition temperatures highlight the stability of the compounds. The decomposition reactions are discussed in terms of DSC and TG data, obtained by us and other researchers.

Comparative study on heat stability of camel and bovine apo and holo α-lactalbumin

2009 ◽  
Vol 77 (1) ◽  
pp. 43-49 ◽  
Author(s):  
Maliheh Sadat Atri ◽  
Ali Akbar Saboury ◽  
Reza Yousefi ◽  
Michèle Dalgalarrondo ◽  
Jean-Marc Chobert ◽  
...  
Keyword(s):  
Thermal Stability ◽  
Differential Scanning Calorimetry ◽  
Heat Capacity ◽  
Secondary Structure ◽  
Hydrophobic Interactions ◽  
Heat Stability ◽  
Heat Denaturation ◽  
Scanning Calorimetry ◽  
The Difference ◽  
The Stability

The stability of camel α-lactalbumin (α-la) against heat denaturation was measured, using circular dichroism (CD) and fluorescence spectroscopy, as well as differential scanning calorimetry (DSC). The experiments were performed in the presence of saturating concentrations of calcium as well as in the presence of EDTA, yielding to the apo form of α-la. The change in heat capacity (ΔCp) suggests a greater contribution of hydrophobic interactions to the stability of holo camel α-la than in its bovine counterpart. Overall the results obtained in this study suggest a greater stability of camel α-la than the bovine protein in both holo and apo states. Also CD experiments showed similar secondary structure for camel and bovine α-la and secondary structure of camel α-la was better preserved than that of bovine α-la during heat denaturation. The differences in thermal stability between the proteins from two species can be primarily ascribed to the difference in the quantity of hydrophobic interactions involved in their folding.

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