scholarly journals Using Size-Exclusion Chromatography to Monitor Variations in the Sizes of Microwave-Irradiated Gold Nanoparticles

2012 ◽  
Vol 2012 ◽  
pp. 1-7 ◽  
Author(s):  
Fu-Ken Liu
Keyword(s):  
Gold Nanoparticles ◽  
Size Exclusion Chromatography ◽  
Ostwald Ripening ◽  
Sodium Dodecyl ◽  
Irradiation Temperature ◽  
Operating Conditions ◽  
Size Exclusion ◽  
Au Nps ◽  
Exclusion Chromatography ◽  
Mw Irradiation

Size-exclusion chromatography (SEC) was used to evaluate gold nanoparticles (Au NPs) for variations in their sizes after microwave (MW) irradiation, with the eluted NPs monitored through diode array detection to reveal their surface plasmon absorptions. The sizes of citrate-capped Au NPs decreased upon increasing the MW irradiation temperature, consistent with digestive ripening of these NPs under the operating conditions. In contrast, Au NPs capped with sodium dodecyl sulfate increased in size upon increasing the MW irradiation temperature, consistent with Ostwald ripening. When the Au NPs were capped with 3A-amino-3A-deoxy-(2AS,3AS)--cyclodextrin (H2N--CD), however, their dimensions were barely affected by the MW irradiation temperature, confirming that H2N--CD is a good stabilizer against MW irradiation. Therefore, SEC—with its short analysis times, low operating costs, automated operation, and in situ analysis—has great potential for use in the rapid monitoring of NPs subjected to treatment under various MW irradiation conditions.

scholarly journals Characterization of a Novel β-Galactosidase fromBifidobacterium adolescentis DSM 20083 Active towards Transgalactooligosaccharides

2000 ◽  
Vol 66 (4) ◽  
pp. 1379-1384 ◽  
Author(s):  
Katrien M. J. Van Laere ◽  
Tjakko Abee ◽  
Henk A. Schols ◽  
Gerrit Beldman ◽  
Alphons G. J. Voragen
Keyword(s):  
Size Exclusion Chromatography ◽  
Polyacrylamide Gel Electrophoresis ◽  
Sodium Dodecyl ◽  
Cell Extract ◽  
Degree Of Polymerization ◽  
Exchange Chromatography ◽  
Size Exclusion ◽  
Bifidobacterium Adolescentis ◽  
Exclusion Chromatography

ABSTRACT This paper reports on the effects of both reducing and nonreducing transgalactooligosaccharides (TOS) comprising 2 to 8 residues on the growth of Bifidobacterium adolescentis DSM 20083 and on the production of a novel β-galactosidase (β-Gal II). In cells grown on TOS, in addition to the lactose-degrading β-Gal (β-Gal I), another β-Gal (β-Gal II) was detected and it showed activity towards TOS but not towards lactose. β-Gal II activity was at least 20-fold higher when cells were grown on TOS than when cells were grown on galactose, glucose, and lactose. Subsequently, the enzyme was purified from the cell extract of TOS-grown B. adolescentis by anion-exchange chromatography, adsorption chromatography, and size-exclusion chromatography. β-Gal II has apparent molecular masses of 350 and 89 kDa as judged by size-exclusion chromatography and sodium dodecyl sulfate-polyacrylamide gel electrophoresis, respectively, indicating that the enzyme is active in vivo as a tetramer. β-Gal II had an optimal activity at pH 6 and was not active below pH 5. Its optimum temperature was 35°C. The enzyme showed highestV max values towards galactooligosaccharides with a low degree of polymerization. This result is in agreement with the observation that during fermentation of TOS, the di- and trisaccharides were fermented first. β-Gal II was active towards β-galactosyl residues that were 1→4, 1→6, 1→3, and 1↔1 linked, signifying its role in the metabolism of galactooligosaccharides by B. adolescentis.

Conformational change and inactivation of arginine kinase from shrimpFeneropenaeus chinensisin oxidized dithiothreitol solutions

2004 ◽  
Vol 82 (3) ◽  
pp. 361-367 ◽  
Author(s):  
Ji-Cheng Pan ◽  
Zhen-Hang Yu ◽  
En-Fu Hui ◽  
Hai-Meng Zhou
Keyword(s):  
Conformational Change ◽  
Size Exclusion Chromatography ◽  
Tertiary Structure ◽  
Arginine Kinase ◽  
Sodium Dodecyl ◽  
Size Exclusion ◽  
Excitation Wavelength ◽  
Ans Binding ◽  
Sds Page ◽  
Exclusion Chromatography

The effect of oxidized dithiothreitol (DTT) on the conformation and function of arginine kinase from shrimp Feneropenaeus chinensis was investigated with the methods of intrinsic fluorescence, ANS fluorescence, size exclusion chromatography (SEC), sodium dodecyl sulfate – polyacrylamide gel electrophoresis (SDS–PAGE), and activity assay. The excess molecular oxidized dithiothreitol could result in a loss of activity and conformational change of arginine kinase. The oxidized arginine kinase was characterized by monitoring the changes of fluorescence emission wavelength (excitation wavelength: 295 nm) and the intensity of 1-anilino-8-naphthalenesulfonate (ANS) binding (excitation wavelength: 380 nm) to the protein. The results of fluorescence spectra showed that the presence of oxidized DTT could result in a marked change in the enzyme tertiary structure. The conformational changes of native and oxidized arginine kinase are induced by the presence of the full set of transition state analog (TSA) components. The results of size exclusion chromatography and SDS–PAGE indicated that no disulfide bond was formed among the protein molecules in the oxidized-DTT solution.Key words: arginine kinase, oxidized dithiothreitol, conformational change, inactivation.

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