A calorimetric study of the thermal transitions of Halobacterium cutirubrum

1982 ◽  
Vol 60 (4) ◽  
pp. 419-421 ◽  
Author(s):  
K. C. Cho ◽  
K. C. Chow ◽  
K. K. Mark
Keyword(s):  
Differential Scanning Calorimetry ◽  
Envelope Glycoprotein ◽  
Hydrophobic Interactions ◽  
Major Protein ◽  
Calorimetric Study ◽  
Thermal Transitions ◽  
Scanning Calorimetry ◽  
Previous Proposal ◽  
Protein Components

The thermal transitions of Halobacterium cutirubrum have been examined by differential scanning calorimetry. Two distinct peaks corresponding to the denaturation of two major protein components were observed in the heating curves. One of the peaks has been assigned to the denaturation of the envelope glycoprotein. The variations of the denaturation temperatures with the addition of glucose, glycerol, NaNO3, and NaSCN are consistent with the previous proposal that hydrophobic interactions are essential in stabilizing the glycoprotein.

scholarly journals A calorimetric study of human CuZn superoxide dismutase

1987 ◽  
Vol 248 (3) ◽  
pp. 981-984 ◽  
Author(s):  
C G Biliaderis ◽  
R J Weselake ◽  
A Petkau ◽  
A D Friesen
Keyword(s):  
Differential Scanning Calorimetry ◽  
Binding Sites ◽  
Specific Activity ◽  
Calorimetric Study ◽  
Thermal Transitions ◽  
Scanning Calorimetry ◽  
Structural Units ◽  
Conformational Order ◽  
Higher Temperature ◽  
Cuzn Superoxide Dismutase

Structural alterations, as manifested by thermal transitions, caused by removal or binding of metal ions to human and bovine CuZn superoxide dismutases (SODs) were investigated by differential scanning calorimetry. Although holo forms of the two mammalian enzymes exhibited irreversible thermal transitions (delta Hcal. = 27.7 J/g and Td = 104 degrees C for bovine SOD; delta Hcal. = 23.6 J/g and Td = 101 degrees C for human SOD), only the bovine apoenzyme showed the presence of a less thermostable form (delta Hcal. = 10.7 J/g and Td = 63 degrees C). These observations suggested that human apo-SOD had considerably less conformational order than bovine apo-SOD. Reconstitution of human and bovine apoenzymes with Cu2+ and Zn2+ resulted in recovery of thermodynamic parameters and specific activity. Binding of Zn2+ alone to human apo-SOD resulted in the formation of two distinct structural units, detectable by differential scanning calorimetry, which underwent conformational disorder at 82 and 101 degrees C respectively. Saturation of binding sites with both Zn2+ and Cu2+ appeared to stabilize the enzyme structure further as shown by elimination of the low-temperature transition and the appearance of another thermal transition at a higher temperature.

scholarly journals Calorimetric study on Bi-Cu-Sn alloys

2019 ◽  
Vol 38 (2019) ◽  
pp. 541-546
Author(s):  
Jolanta Romanowska
Keyword(s):  
Differential Scanning Calorimetry ◽  
Electron Microscope ◽  
Scanning Electron Microscope ◽  
Temperature Interval ◽  
Energy Dispersive Spectrometer ◽  
Energy Dispersive ◽  
Calorimetric Study ◽  
Calorimetric Investigation ◽  
Scanning Calorimetry ◽  
Scanning Electron

AbstractThe paper presents results of calorimetric investigation of the Bi-Cu-Sn system by means of differential scanning calorimetry (DSC) at the temperature interval 25-1250∘C, Values of liquidus, solidus and invariant reactions temperatures, as well as melting enthalpies of the selected alloys were determined. Microstructure investigation of the alloys were performed by the use of a scanning electron microscope (SEM) equipped with an energy-dispersive spectrometer (EDS).

Comparison of the Thermal Transitions of Spray-Dried and Freeze-Dried Egg Whites by Differential Scanning Calorimetry

2020 ◽  
Vol 13 (8) ◽  
pp. 1329-1343
Author(s):  
Jin-Hong Zhao ◽  
Li-Sha Liu ◽  
Shyam S. Sablani ◽  
Yi-Jiao Peng ◽  
Hong-Wei Xiao ◽  
...  
Keyword(s):  
Differential Scanning Calorimetry ◽  
Thermal Transitions ◽  
Scanning Calorimetry ◽  
Freeze Dried ◽  
Spray Dried

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.

Thermal transitions of king fish whole muscle, fat and fat-free muscle by differential scanning calorimetry

2007 ◽  
Vol 462 (1-2) ◽  
pp. 56-63 ◽  
Author(s):  
S.S. Sablani ◽  
M.S. Rahman ◽  
S. Al-Busaidi ◽  
N. Guizani ◽  
N. Al-Habsi ◽  
...  
Keyword(s):  
Differential Scanning Calorimetry ◽  
Thermal Transitions ◽  
Scanning Calorimetry ◽  
Whole Muscle

Thermal Analysis of Fresh and Mature Oil Paint Films: The Effect of Pigments as Driers and the Solvent Leaching of Mature Paint Films

1990 ◽  
Vol 185 ◽  
Author(s):  
Christopher W. McGlinchey
Keyword(s):  
Thermal Analysis ◽  
Differential Scanning Calorimetry ◽  
Linseed Oil ◽  
Glass Transitions ◽  
Lead White ◽  
Thermal Transitions ◽  
Scanning Calorimetry ◽  
Titanium White ◽  
Drying Properties ◽  
Paint Films

AbstractThe effect of titanium white, zinc white and lead white on the drying properties of poppy, walnut and linseed oil are analyzed by differential scanning calorimetry (DSC). All of the fresh films undergo complex thermal transitions between -100 and O°C. For some of the dried films subambient transitions that resemble glass transitions occur at about -30 O°C. After exposure to certain solvents, these sub-ambient transitions disappear or are reduced significantly. It is suggested that samples with diminished sub-ambient transitions become more brittle as a result of the loss of materials that act as plasticizers.

Calorimetric Study of the Energetics and Kinetics of Interdiffusion in Cu/Cu6sn5 Thin Film Diffusion Couples

1995 ◽  
Vol 398 ◽  
Author(s):  
W. K. Neils ◽  
R. R. Chromik ◽  
K. F. Dreyer ◽  
D. Grosman ◽  
E. J. Cotts
Keyword(s):  
Differential Scanning Calorimetry ◽  
Bulk Diffusion ◽  
Heat Of Formation ◽  
Calorimetric Study ◽  
Diffusion Couples ◽  
Scanning Calorimetry ◽  
Metal Diffusion ◽  
Diffusion Limited ◽  
Thin Film Diffusion ◽  
Kinetics Of

ABSTRACTWe find differential scanning calorimetry to be suitable for the characterization of the energetics and kinetics of interdiflusion in solder/metal diffusion couples. Differential scanning calorimetry studies of interdiffusion in Cu/Cu6Sn5 diffusion couples have shown that the driving force for interdiffusion is similar for thin film composites and for bulk diffusion couples. The heat of formation of Cu3Sn from Cu6Sn5 and Cu thin films was found to be ΔHr = −4.3 + 0.3 kJ/mol. Portions of our differential scanning calorimetry scans are identified with diffusion limited growth of Cu3Sn. From these calorimetry data we have estimated D(cm2 / s) = Do exp(−E / kbT), where kb is Boltzmann's constant, D0 = 3.2 × 10–2 cm2/s, and E=0.87 eV/atom.

scholarly journals A calorimetric study of the thermal denaturation of whey proteins in simulated milk ultrafiltrate

1977 ◽  
Vol 44 (3) ◽  
pp. 509-520 ◽  
Author(s):  
M. Rüegg ◽  
Ursula Moor ◽  
B. Blanc
Keyword(s):  
Heat Treatment ◽  
Xanthine Oxidase ◽  
Conformational Changes ◽  
Thermal Denaturation ◽  
Whey Proteins ◽  
Calorimetric Study ◽  
Thermal Transitions ◽  
Scanning Calorimetry ◽  
Β Lactoglobulin ◽  
Dsc Thermograms

SummaryDifferential scanning calorimetry (DSC) was used to study thermal transitions of the following whey proteins and enzymes in milk ultrafiltrate solution: β-lactoglobulin, α-lactalbumin, serum albumin, γ-globulin, apo- and Fe-lactoferrin, lysozyme, ribonuclease, α-chymotrypsin and xanthine oxidase. Denaturation enthalpies (ΔHD), denaturation temperatures (TD) and the half width of the denaturation peaks in DSC thermograms (ΔT½D) were determined and the degree of renaturation was estimated by rescanning previously denatured samples. A fair correlation between the results obtained by DSC and other more classical methods was found in general. However, for some proteins (α-lactalbumin, lysozyme, ribonuclease and xanthine oxidase), which have so far been considered relatively thermostable, calorimetry reveals conformational changes starting at temperatures as low as about 45 °C. In these cases thermostability observed after heat treatment of milk should be interpreted in terms of renaturation and not of high temperatures of denaturation.

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