- G. Gianese (1)
- W.E. Hennink (1)
- M.A. Hink (1)
- A. Hoek van (1)
- A. Iordanidis (1)
- W. Jiskoot (1)
- B. Lagen van (1)
- J.F.T. Lieshout van (1)
- B. Lucas (1)
- S. Oliveira (1)
- J. Oost van der (1)
- N.N. Sanders (1)
- J. Schwarzbauer (1)
- S.C. Smedt de (1)
- M. Sutter (1)
- A.J.W.G. Visser (1)
Organic geochemistry of Amynteo lignite deposit, northern Greece: a Multi-analytical approach
Iordanidis, A. ; Schwarzbauer, J. ; Georgakopoulos, A. ; Lagen, B. van - \ 2012
Geochemistry international 50 (2012)2. - ISSN 0016-7029 - p. 159 - 178.
maritza-east lignite - c-13 cp/mas nmr - rich mine soils - bituminous coal - brown-coal - ftir spectroscopy - humic substances - new-zealand - crude oils - py-gc/ms
Several lignite samples were collected from boreholes of the Amynteo opencast lignite mine, northern Greece. Organic geochemical characteristics were investigated with the help of various analytical techniques, comprising Gas Chromatography (GC) and Gas-chromatography-Mass Spectrometry (GC-MS), Fourier Transform Infrared Spectroscopy (FTIR), solid-state Nuclear Magnetic Resonance (NMR) and Electron Paramagnetic Resonance (EPR) spectroscopy, petrographical measurements as well as determination of bulk parameters. In the low rank (Rr = 0.21%) Amynteo lignites, huminite is the most abundant maceral group, inertinite has relatively low percentages and liptinite concentrations are rather high. Carbon Preference Index (CPI) reveals the predominance of odd-numbered, long-chained aliphatic hydro-carbons, which is related to a higher terrestrial plant input. The Pr/Ph ratio suggests that reducing conditions were persistent during peatification. Gymnosperm biomarkers such as isoprimarane, abietane, phyllocladane and sandaracopimarane, as well as angiosperm indicators (lupane) and hopanoid compounds with bacterial origin were identified. Analyses of the aromatic fractions revealed the presence of naphthalene, alkyl benzenes and phenols, pyrene, cadalene, cadinane, fluoranthene and dibenzofurane. Based on the FTIR analysis, aliphatic and oxygen containing structures were prevailed over the aromatic moieties. The intensity of the mineral bands was preferentially increased in the FTIR spectra of insoluble material. According to NMR analysis, the aliphatic carbons (0-50 ppm) have higher proportions comparing to aromatic carbons (100-160 ppm). The aromaticity fraction is low (fa = 0.32), as expected for these low rank coals. The presence of free organic radicals and Fe3+ and Mn2+ paramagnetic ions was revealed by EPR. In summary, the combined application of complementary analytical techniques allowed a deep inside into the geochemical characteristics of Amynteo lignites.
Sensitive spectroscopic detection of large and denatured protein aggregates in solution by use of the fluorescent dye Nile re
Sutter, M. ; Oliveira, S. ; Sanders, N.N. ; Lucas, B. ; Hoek, A. van; Hink, M.A. ; Visser, A.J.W.G. ; Smedt, S.C. de; Hennink, W.E. ; Jiskoot, W. - \ 2007
Journal of Fluorescence 17 (2007)2. - ISSN 1053-0509 - p. 181 - 192.
galactosidase escherichia-coli - beta-galactosidase - ftir spectroscopy - congo red - immunogenicity - surfaces - probe
The fluorescent dye Nile red was used as a probe for the sensitive detection of large, denatured aggregates of the model protein ß-galactosidase (E. coli) in solution. Aggregates were formed by irreversible heat denaturation of ß-galactosidase below and above the protein¿s unfolding temperature of 57.4°C, and the presence of aggregates in heated solutions was confirmed by static light scattering. Interaction of Nile red with ß-galactosidase aggregates led to a shift of the emission maximum (¿ max) from 660 to 611 nm, and to an increase of fluorescence intensity. Time-resolved fluorescence and fluorescence correlation spectroscopy (FCS) measurements showed that Nile red detected large aggregates with hydrodynamic radii around 130 nm. By steady-state fluorescence measurements, it was possible to detect 1 nM of denatured and aggregated ß-galactosidase in solution. The comparison with size exclusion chromatography (SEC) showed that native ß-galactosidase and small aggregates thereof had no substantial effect on the fluorescence of Nile red. Large aggregates were not detected by SEC, because they were excluded from the column. The results with ß-galactosidase demonstrate the potential of Nile red for developing complementary analytical methods that overcome the size limitations of SEC, and can detect the formation of large protein aggregates at early stages.
Calcium-induced tertiary structure modifications of endo-B-1,3-glucanase form Pyrococcus furiosus in 7.9 M guanidinium chloride
Chiaraluce, R. ; Gianese, G. ; Angelaccio, S. ; Florio, R. ; Lieshout, J.F.T. van; Oost, J. van der; Consalvi, V. - \ 2005
Biochemical Journal 386 (2005)3. - ISSN 0264-6021 - p. 515 - 524.
transform infrared-spectroscopy - protein secondary structure - 3-dimensional structures - ftir spectroscopy - free-energy - recognition - database - endo-beta-1,3-glucanase - intermediate - alignments
The family 16 endo-b-1,3 glucanase from the extremophilic archaeon Pyrococcus furiosus is a laminarinase, which in 7.9 M GdmCl (guanidinium chloride) maintains a significant amount of tertiary structure without any change of secondary structure. The addition of calcium to the enzyme in 7.9 M GdmCl causes significant changes to the near-UV CD and fluorescence spectra, suggesting a notable increase in the tertiary structure which leads to a state comparable, but not identical, to the native state. The capability to interact with calcium in 7.9 M GdmCl with a consistent recovery of native tertiary structure is a unique property of this extremely stable endo-b-1,3 glucanase. The effect of calcium on the thermodynamic parameters relative to the GdmCl-induced equilibrium unfolding has been analysed by CD and fluorescence spectroscopy. The interaction of calcium with the native form of the enzyme is studied by Fourier-transform infrared spectroscopy in the absorption region of carboxylate groups and by titration in the presence of a chromophoric chelator. A homology-based model of the enzyme is generated and used to predict the putative binding site(s) for calcium and the structural interactions potentially responsible for the unusual stability of this protein, in comparison with other family 16 glycoside hydrolases