Characterization of Thermal Stability of the Escherichia coli Fapy–DNA Glycosylase

2001 ◽  
Vol 288 (1) ◽  
pp. 121-128 ◽  
Author(s):  
Serguei V. Kuznetsov ◽  
Olga M. Sidorkina ◽  
Jacques Laval ◽  
Anjum Ansari
Keyword(s):  
Escherichia Coli ◽  
Thermal Stability ◽  
Dna Glycosylase ◽  
Thermal Stability Of

scholarly journals Molecular Characterization of Cycloinulooligosaccharide Fructanotransferase from Bacillus macerans

2001 ◽  
Vol 67 (2) ◽  
pp. 995-1000 ◽  
Author(s):  
Hwa-Young Kim ◽  
Yong-Jin Choi
Keyword(s):  
Escherichia Coli ◽  
Thermal Stability ◽  
Striking Difference ◽  
Bacillus Macerans ◽  
Specific Manner ◽  
Specificity Constant ◽  
Processing Event ◽  
Hydrolysis Of ◽  
Thermal Stability Of

ABSTRACT Cycloinulooligosaccharide fructanotransferase (CFTase) converts inulin into cyclooligosaccharides of β-(2→1)-linkedd-fructofuranose by catalyzing an intramolecular transfructosylation reaction. The CFTase gene was cloned and characterized from Bacillus macerans CFC1. The CFTase gene encoded a polypeptide of 1,333 amino acids with a calculatedM r of 149,563. Western blot and zymography analyses revealed that the CFTase with a molecular mass of 150 kDa (CFT150) was processed (between Ser389 and Phe390 residue) to form a 107-kDa protein (CFT107) in the B. macerans CFC1 cells. The processed CFT107 was similar in its mass to the previously purified CFTase from B. macerans CFC1. The CFT107 enzyme was produced by B. macerans CFC1 but was not detected from the recombinant Escherichia coli cells, indicating that the processing event occurred in a host-specific manner. The two CFTases (CFT150 and CFT107) exhibited the same enzymatic properties, such as influences of pH and temperature on the enzyme activity, the intermolecular transfructosylation ability, and the ability of hydrolysis of cycloinulooligosaccharides produced by the cyclization reaction. However, the thermal stability of CFT107 was slightly higher than that of CFT150. The most striking difference between the two enzymes was observed in their Km values; the value for CFT150 (1.56 mM) was threefold lower than that for CFT107 (4.76 mM). Thus, the specificity constant (k cat/Km ) of CFT150 was about fourfold higher than that of CFT107. These results indicated that the N-terminal 358-residue region of CFT150 played a role in increasing the enzyme's binding affinity to the inulin substrate.

Purification and characterization of Escherichia coli formamidopyrimidine-DNA glycosylase that excises damaged 7-methylguanine from deoxyribonucleic acid

Biochemistry ◽  
1981 ◽  
Vol 20 (18) ◽  
pp. 5201-5207 ◽  
Author(s):  
Christopher J. Chetsanga ◽  
Marie Lozon ◽  
Christopher Makaroff ◽  
Laura Savage
Keyword(s):  
Escherichia Coli ◽  
Deoxyribonucleic Acid ◽  
Dna Glycosylase ◽  
Purification And Characterization

scholarly journals Preparation and characterization of polyhedral oligomeric silsesquioxane/polystyrene nanocomposites

e-Polymers ◽  
2012 ◽  
Vol 12 (1) ◽  
Author(s):  
Benhong Yang ◽  
Meng Li ◽  
Yun Wu ◽  
Kang Wang
Keyword(s):  
Thermal Stability ◽  
Thermal Property ◽  
Polyhedral Oligomeric Silsesquioxane ◽  
29Si Nmr ◽  
Solution Blending ◽  
Oligomeric Silsesquioxane ◽  
Tga And Dsc ◽  
Thermal Stability Of

AbstractSeveral inorganic/organic nanocomposites were prepared via solution-blending of cage-like octahexyl-polyhedral oligomeric silsesquioxane (Oh-POSS) with polystyrene (PS) in THF solvent. FTIR and 29Si-NMR were employed to characterize the structures of the nanocomposites. SEM pictures showed that the sample films were smooth and no POSS aggregation was observed when POSS content was lower than 1.0 wt%. TGA and DSC were used to investigate the thermal property. The results showed that the incorporation of nanosized Oh-POSS enhanced the thermal stability of PS with low POSS content. When 1.0 wt% of Oh-POSS was incorporated into PS matrix, the Tg and Td increased by 7.7 °C and 8.2 °C, respectively. However, higher POSS contents (>1.0 wt%) would deteriorate the thermal property of the nanocomposites due to the severe congregation of POSS..

Systematic Characterization of Different Quaternary Ammonium Salts to be Used in Organoclays

2012 ◽  
Vol 727-728 ◽  
pp. 1552-1556
Author(s):  
Renata Barbosa ◽  
Dayanne Diniz Souza ◽  
Edcleide Maria Araújo ◽  
Tomás Jefférson Alves de Mélo
Keyword(s):  
Thermal Stability ◽  
Quaternary Ammonium ◽  
Chemical Structure ◽  
Quaternary Ammonium Salts ◽  
Ammonium Salts ◽  
Degradation Mechanisms ◽  
Scanning Calorimetry ◽  
Higher Temperature ◽  
Thermal Stability Of

Studies of degradation have verified that the decomposition of some quaternary ammonium salts can begin to be significant at the temperature of about 180 ° C and like most thermoplastics are processed at least around this temperature, the thermal stability of the salt in clay should always be considered. Some salts are more stable than others, being necessary to study the degradation mechanisms of each case. In this work, four quaternary ammonium salts were characterized by differential scanning calorimetry (DSC) and thermogravimetry (TG). The results of DSC and TG showed that the salts based chloride (Cl-) anion begin to degrade at similar temperatures, while the salt based bromide (Br-) anion degrades at higher temperature. Subsequently, a quaternary ammonium salt was chosen to be used in organoclays, depending on its chemical structure and its thermal behavior.

Synthesis and Characterization of Some Functional Luminol Derivatives with Aromatic Substituted Groups

2011 ◽  
Vol 197-198 ◽  
pp. 606-609 ◽  
Author(s):  
Ti Feng Jiao ◽  
Yuan Yuan Xing ◽  
Jing Xin Zhou ◽  
Wei Wang
Keyword(s):  
Molecular Structure ◽  
Thermal Stability ◽  
Molecular Structures ◽  
Synthesis And Characterization ◽  
Functional Material ◽  
Aromatic Substituent ◽  
The Difference ◽  
Imide Group ◽  
Thermal Stability Of

Some functional luminol derivatives with aromatic substituted groups have been designed and synthesized from the reaction of the corresponding aromatic acyl chloride precursors with luminol. It has been found that depending on the size of aromatic groups, the formed luminol derivatives showed different properties, indicating distinct regulation of molecular skeletons. UV and IR data confirmed commonly the formation of imide group as well as aromatic segment in molecular structures. Thermal analysis showed that the thermal stability of luminol derivatives with p-phthaloyl segment was the highest in those derivatives. The difference of thermal stability is mainly attributed to the formation of imide group and aromatic substituent groups in molecular structure. The present results have demonstrated that the special properties of luminol derivatives can be turned by modifying molecular structures of objective compounds with proper substituted groups, which show potential application in functional material field and ECL sensor.

KARBON LİF ÜRETİMİNDE POLİAKRİLONİTRİL ELYAFLARIN TERMAL OKSİDASYONU

2021 ◽  
Vol 8 (17) ◽  
pp. 160-170
Author(s):  
Mahbubor Rahman ◽  
Tuba DEMIREL ◽  
Ismail KARACAN
Keyword(s):  
Thermal Stability ◽  
Aqueous Solution ◽  
Thermal Oxidation ◽  
Oxidation Process ◽  
Ammonium Persulfate ◽  
Oxidation Reactions ◽  
Carbon Yield ◽  
Thermal Stability Of ◽  
Pan Fibers

Thermal oxidation of polyacrylonitrile (PAN) fibers was accomplished at temperatures up to 250°C for different oxidation times. Chemical integration of PAN fibers with an aqueous solution of ammonium persulfate was performed before starting thermal oxidation. The results recommend that ammonium persulfate integration enhanced the oxidation reactions of the PAN fibers and resulting in enhanced thermal stability. Ammonium persulfate impregnation followed by the oxidation process in the air environment leads to significant deviations in the characteristics of PAN fibers. To perform structural characterization of the raw and ammonium persulfate (APS) incorporated and stabilized samples, XRD, IR-spectroscopy, TGA was executed in this study. Investigation of the XRD and infrared spectroscopy outcomes recommended quick aromatization reactions with growing oxidation periods. The TGA traces indicated a comparative enhancement in the thermal stability of the PAN fibers by the increased carbon yield with the rise of the oxidation time. The overall findings recommend that ammonium persulfate incorporation was very influential in stimulating the oxidation process.

Preparation and characterization of phase-change energy storage nonwoven fabric

2021 ◽  
pp. 152808372110417
Author(s):  
Zhou Zhao ◽  
Ningning Tong ◽  
Hong Song ◽  
Yan Guo ◽  
Jinmei Wang
Keyword(s):  
Phase Transition ◽  
Thermal Stability ◽  
Energy Storage ◽  
Phase Change ◽  
Nonwoven Fabric ◽  
Scanning Calorimetry ◽  
Change Material ◽  
Stretching Process ◽  
Thermal Stability Of

In this work, a phase-change energy storage nonwoven fabric was made of polyurethane phase-change material (PUPCM) by a non-woven melt-blown machine. Polyethylene glycol 2000 was used as the phase transition unit and diphenyl-methane-diisocyanate as the hard segment to prepare PUPCM. Thermal stability of the PUPCM was evaluated through thermal stability analysis. The performance of pristine PUPCM was determined by Fourier transform infrared spectroscopy and differential scanning calorimetry to analyze the spinning technology of spinning temperature and the stretching process. Phase-change energy storage nonwoven fabric (413.22 g/m2) was prepared, and the morphology, solid–solid exothermic phase transition, mechanical properties, and the structures were characterized. The enthalpy of solid–solid exothermic phase transition reached 60.17 mJ/mg (peaked at 23.14°C). The enthalpy of solid–solid endothermic phase transition reached 67.09 mJ/mg (peaked at 34.34°C). The strength and elongation of phase-change energy storage nonwoven fabric were found suitable for garments and tent fabrics.

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