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Mobilization of neutral compounds by inorganic and small organic ions in capillary electrophoresis
Křížek, T.; Martínková, E.; Kubíčková, A.; Hladílková, Jana; Coufal, P.; Heyda, J.; Jungwirth, Pavel
2016 - English
The present study shows that neutral low-molecular-mass compounds that are presumed to possess zero electrophoretic mobility and are thus used as markers of electroosmotic flow in capillary electrophoresis can acquire electrophoretic mobility due to ion-specific interactions with constituents of background electrolyte. Therefore, these neutral markers, such as thiourea or dimethyl sulfoxide, can be separated in electric field and their migration order can vary depending on background electrolyte composition. This observation has some important implications for analytical and physico-chemical measurements using capillary electrophoresis because the choice of the marker-background electrolyte combination can influence the results of the measurement.
Keywords:
capillary electrophoresis; EOF markers; ion-specific effects; mobilization
Available at various institutes of the ASCR
Mobilization of neutral compounds by inorganic and small organic ions in capillary electrophoresis
The present study shows that neutral low-molecular-mass compounds that are presumed to possess zero electrophoretic mobility and are thus used as markers of electroosmotic flow in capillary ...
Investigation of calix[4]arene-bis(t-octylbenzo-18-crown-6) complex with cesium cation by affinity capillary electrophoresis
Štěpánová, Sille; Moyer, B.; Makrlík, E.; Kašička, Václav
2016 - English
Affinity capillary electrophoresis (ACE) was employed for investigation of non-covalent interactions of calix[4]arene-bis(t-octylbenzo-18-crown-6) with Cs+ ion in methanol. The apparent binding constant of the calix[4]arene-bis(t-octylbenzo-18-crown-6)-Cs+ complex was determined from the dependence of the effective electrophoretic mobilities of the calix[4]arene-bis(t-octylbenzo-18-crown-6) on the concentration of cesium ion in the backround electrolyte using a non-linear regression analysis. The logarithmic form of the conditional apparent binding constant of calix[4]arene-bis(t-octylbenzo-18-crown-6)-Cs+ complex was found to be equal to 1.61.
Keywords:
affinity capillary electrophoresis; calix[4]arene-bis(t-octylbenzo-18-crown-6); binding constant
Available at various institutes of the ASCR
Investigation of calix[4]arene-bis(t-octylbenzo-18-crown-6) complex with cesium cation by affinity capillary electrophoresis
Affinity capillary electrophoresis (ACE) was employed for investigation of non-covalent interactions of calix[4]arene-bis(t-octylbenzo-18-crown-6) with Cs+ ion in methanol. The apparent binding ...
Determination of stability constant of potassium-dibenzo-18-crown-6 complex in mixed hydro-organic solvents by affinity capillary electrophoresis
Konášová, Renáta; Jaklová Dytrtová, Jana; Kašička, Václav
2016 - English
Affinity capillary electrophoresis was applied to determination of apparent stability constant, Kst, of potassium-dibenzo-18-crown-6 complex in mixed hydro-organic solvents, i.e. mixtures of water with methanol, ethanol, propan-2-ol or acetonitrile. It was found that the Kst strongly depends on the solvent composition. The log Kst values linearly increase with decreasing molar fraction of water in the above hydro-organic solvent mixture.
Keywords:
affinity capillary electrophoresis; dibenzo-18-crown-6; stability constant
Available at various institutes of the ASCR
Determination of stability constant of potassium-dibenzo-18-crown-6 complex in mixed hydro-organic solvents by affinity capillary electrophoresis
Affinity capillary electrophoresis was applied to determination of apparent stability constant, Kst, of potassium-dibenzo-18-crown-6 complex in mixed hydro-organic solvents, i.e. mixtures of water ...
Frustrated Lewis pairs-assisted reduction of carbonyl compounds
Marek, Aleš; Pedersen, M. H. F.
2016 - English
An alternative and robust method for the reduction of carbonyl groups by frustrated Lewis pairs (FLPs) is reported in this paper. With its very mild reaction conditions, good to excellent yields, absolute regioselectivity and the non-metallic character of the reagent, it provides an excellent tool for 1H, 2H as well as 3H chemistry. It is a new strategy for the one-pot synthesis of aromatic alcohols selectively labeled with heavy isotopes of hydrogen.
Keywords:
carbonyl compounds; frustrated Lewis parts; alcohol synthesis
Available at various institutes of the ASCR
Frustrated Lewis pairs-assisted reduction of carbonyl compounds
An alternative and robust method for the reduction of carbonyl groups by frustrated Lewis pairs (FLPs) is reported in this paper. With its very mild reaction conditions, good to excellent yields, ...
Analysis of novel members of FAHFA lipid class derived from omega 3-PUFA by LC-MS/MS and LC-MS/MS/MS
Rombaldová, Martina; Kuda, Ondřej; Březinová, Marie; Slavíková, Barbora; Pošta, Martin; Beier, Petr; Janovská, Petra; Veleba, J.; Kopecký Jr., J.; Kudová, Eva; Pelikánová, T.; Kopecký, Jan
2016 - English
White adipose tissue (WAT) is a complex organ with both metabolic and endocrine functions. Dysregulation of all of these functions of WAT, together with low-grade inflammation of the tissue in obesity, contributes to the development of insulin resistance and type 2 diabetes. Omega-3 polyunsaturated fatty acids (PUFA) of marine origin play an important role in resolution of inflammation and exert beneficial metabolic effects. Using LC-MS/MS method, we elucidated the structures of novel members of fatty acid esters of hydroxy fatty acids (FAHFA), which were present in murine and human serum and WAT after omega-3 PUFA supplementation in diet. These compounds contained DHA esterified to 9- and 13-hydroxyoctadecadienoic acid (HLA) termed 9-DHAHLA and 13-DHAHLA, and were synthesized in WAT. Our results document the existence of novel lipid mediators, which are involved in the beneficial anti-inflammatory effects attributed toomega-3 PUFA, in both miceandhumans.
Keywords:
branched fatty acid; lipidomics; mass spectrometry; omega 3-PUFA
Available at various institutes of the ASCR
Analysis of novel members of FAHFA lipid class derived from omega 3-PUFA by LC-MS/MS and LC-MS/MS/MS
White adipose tissue (WAT) is a complex organ with both metabolic and endocrine functions. Dysregulation of all of these functions of WAT, together with low-grade inflammation of the tissue in ...
Enantioseparations of drugs and catalysts by partial-filling affinity capillary electrophoresis using helquats as chiral selectors
Růžička, Martin; Koval, Dušan; Vávra, Jan; Reyes Gutierrez, Paul Eduardo; Teplý, Filip; Kašička, Václav
2016 - English
Noncovalent molecular interactions between helquats, a new class of dicationic helical extended diquats and selected commonly used negatively charged chiral drugs and catalysts have been investigated using partial-filling affinity capillary electrophoresis (PF-ACE). Three types of interactions of analytes with helquats were observed: (1) medium strong enantioselective interactions, (2) medium strong non-enantioselective interactions and (3) no or very weak non-enantioselective interactions.
Keywords:
affinity capillary electrophoresis; helquats; chiral selector
Available at various institutes of the ASCR
Enantioseparations of drugs and catalysts by partial-filling affinity capillary electrophoresis using helquats as chiral selectors
Noncovalent molecular interactions between helquats, a new class of dicationic helical extended diquats and selected commonly used negatively charged chiral drugs and catalysts have been investigated ...
Estimation of racemization barriers of selected helquats and their derivatives by capillary electrophoresis using sulfated cyclodextrins as chiral selectors
Sázelová, Petra; Koval, Dušan; Severa, Lukáš; Reyes Gutierrez, Paul Eduardo; Jirásek, Michael; Teplý, Filip; Kašička, Václav
2016 - English
The recently developed capillary electrophoretic (CE) method for chiral analysis of helquats (helical N-heteroaromatic dications) was applied to monitoring of racemization of selected helquats and helquat styryl dyes and for the determination of their racemization barriers, i.e. activation Gibbs free energy deltaG≠. deltaG≠ of analyzed compounds was found to be in the range 107.7 – 115.7 kJ/mol.
Keywords:
capillary electrophoresis; helquats; interconversion barrier
Available at various institutes of the ASCR
Estimation of racemization barriers of selected helquats and their derivatives by capillary electrophoresis using sulfated cyclodextrins as chiral selectors
The recently developed capillary electrophoretic (CE) method for chiral analysis of helquats (helical N-heteroaromatic dications) was applied to monitoring of racemization of selected helquats and ...
Analysis of low abundant lipids in vernix caseosa using chromatographic methods and mass spectrometry
Háková, Eva; Míková, R.; Vrkoslav, Vladimír; Plavka, R.; Cvačka, Josef
2015 - English
The aim of this work is to develop a separation method for characterization of unknown lipids in vernix caseosa. We focused on very low abundant lipids which have not been previously described in vernix caseosa. The total lipid extract was fractionated using low pressure normal phase liquid chromatography to obtain sub-fractions. The sub-fractions were further separated in high performance liquid chromatography mode to isolate classes of lipids. This procedure enabled us to characterise lipid classes by mass spectrometry and identify one of the class as acyl-ceramides with non-hydroxylated fatty acids.
Keywords:
lipids; high performance liquid chromatography; mass spectrometry; vernix caseosa
Available at various institutes of the ASCR
Analysis of low abundant lipids in vernix caseosa using chromatographic methods and mass spectrometry
The aim of this work is to develop a separation method for characterization of unknown lipids in vernix caseosa. We focused on very low abundant lipids which have not been previously described in ...
Insect repellent and feeding deterrent activity of natural sesquiterpene lactones and their derivatives
Adekenov, S. M.; Mukhametzhanova, G. M.; Atazhanova, G. A.; Harmatha, Juraj
2015 - English
Thirty compounds were investigated in order to detect their repellent and antifeedant activity. The substances were tested on several insect test-objects: Sitophilus granarius, Tribolium confusum and Trogoderma granarium. Five sesquiterpene alpha-exometylene-gamma-lactones and one structurally transformed dimethylamino derivative showed high antifeedant and repellent activities.
Keywords:
sesquiterpene lactones; stored product pests
Available at various institutes of the ASCR
Insect repellent and feeding deterrent activity of natural sesquiterpene lactones and their derivatives
Thirty compounds were investigated in order to detect their repellent and antifeedant activity. The substances were tested on several insect test-objects: Sitophilus granarius, Tribolium confusum and ...
Chiroptical spectroscopy as a sensitive tool for the conformational analysis of antimicrobial peptides
Kocourková, L.; Novotná, P.; Čujová, Sabína; Čeřovský, Václav; Urbanová, M.; Setnička, V.
2015 - English
We tested the utilization of electronic and vibrational circular dichroism for the conformational study of antimicrobial peptides on two examples: melectin and antapin in different solutions of liposomes and micelles mimicking bacterial or eukaryotic membranes. The results show significant content of the alpha-helical conformation in an environment mimicking the bacterial membrane, while it was considerably low in the eukaryotic membrane-mimicking environment.
Keywords:
antimicrobial peptides; circular dichroism; conformation; liposomes; model membranes
Available at various institutes of the ASCR
Chiroptical spectroscopy as a sensitive tool for the conformational analysis of antimicrobial peptides
We tested the utilization of electronic and vibrational circular dichroism for the conformational study of antimicrobial peptides on two examples: melectin and antapin in different solutions of ...
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