Affinity capillary electrophoretic study of K+/Na+ selectivity of hexaarylbenzene-based polyaromatic receptor

Affinity capillary electrophoretic (ACE) study has proved the selectivity of hexaarylbenzene-based polyaromatic receptor (R) for K+ ion over Na+ ion. The apparent binding constants of the R complexes with K+ and Na+ ions were determined from the dependence of effective electrophoretic mobility of R on the concentration of the above alkali metal ions in the background electrolyte using a non-linear regression analysis. The apparent binding constants (Kb) of the K-R+ and Na–R+ complexes in methanolic medium were evaluated as log Kb = 3.20 ± 0.22 for the K–R+ complex, and log Kb≅−0.7 for the Na–R+ complex

Mono-\u3cem\u3eN\u3c/em\u3e-acyl-2,6-diaminopimelic Acid Derivatives: Analysis by Electromigration and Spectroscopic Methods and Examination of Enzyme Inhibitory Activity

Thirteen mono-N-acyl derivatives of 2,6-diaminopimelic acid (DAP)—new potential inhibitors of the dapE-encoded N-succinyl-l,l-diaminopimelic acid desuccinylase (DapE; EC 3.5.1.18)—were analyzed and characterized by infrared (IR) and nuclear magnetic resonance (NMR) spectroscopies and two capillary electromigration methods: capillary zone electrophoresis (CZE) and micellar electrokinetic chromatography (MEKC). Structural features of DAP derivatives were characterized by IR and NMR spectroscopies, whereas CZE and MEKC were applied to evaluate their purity and to investigate their electromigration properties. Effective electrophoretic mobilities of these compounds were determined by CZE in acidic and alkaline background electrolytes (BGEs) and by MEKC in acidic and alkaline BGEs containing a pseudostationary phase of anionic detergent sodium dodecyl sulfate (SDS) or cationic detergent cetyltrimethylammonium bromide (CTAB). The best separation of DAP derivatives, including diastereomers of some of them, was achieved by MEKC in an acidic BGE (500 mM acetic acid [pH 2.54] and 60 mM SDS). All DAP derivatives were examined for their ability to inhibit catalytic activity of DapE from Haemophilus influenzae (HiDapE) and ArgE from Escherichia coli (EcArgE). None of these DAP derivatives worked as an effective inhibitor of HiDapE, but one derivative—N-fumaryl, Me-ester-DAP—was found to be a moderate inhibitor of EcArgE, thereby providing a promising lead structure for further studies on ArgE inhibitors

N,N′-Diethyl-N,N′-diphenyl­pyridine-2,6-dicarboxamide

The asymmetric unit of the title compound, C23H23N3O2, contains two mol­ecules in both of which, one amide N atom is in a syn position with respect to the pyridine N atom, while the other amide N atom is in an anti position (the syn--anti conformation). There are minor conformational differences between the two mol­ecules, as reflected in the Npyridine—C—C—Namide torsion angles of −44.9 (3) and 136.0 (2)° for one mol­ecule and 43.5 (3) and −131.1 (2)° for the other mol­ecule. However, the two mol­ecules show significant differences in the orientation of an ethyl group, with corresponding C—C—N—C torsion angles of 86.6 (3)° for one mol­ecule and 79.6 (3)° for the other mol­ecule. In the crystal, mol­ecules are linked by weak C—H⋯O hydrogen bonds, forming a three-dimensional supra­molecular network

Investigation of peptide complexes with small cations and cyclodextrins by capillary affinity electrophoresis

Capillary affinity electrophoresis was applied to quantitative evaluation of the strength of the complexes of i) valinomycin, macrocyclic dodecadepsipeptide ionophore, with small cations (ammonium and alkali metal ions, Li+, Na+, K+, Rb+ and Cs+) in methanol, and ii) enantiomers of dipeptide beta-alanyl-D,L-tyrosine and its derivatives with a chiral selector, 2 hydroxypropyl-beta-cyclodextrin (2-HP-beta-CD), in water

Recent applications of capillary electrophoresis to analysis and physicochemical characterization of peptides

Recent developments in the methodology of capillary electrophoresis are presented with respect to their application to analysis, separation and physicochemical characterization of biologically active peptides. New strongly acidic/basic classical and isoelectric background electrolytes were applied to high-sensitive analysis and high-efficient separations of structurally related peptides, such as insect oostatic and antimicrobial peptides, phosphinic pseudopeptides and tryptic peptide fragments of proteins from native and genetically modified maize species

Separace a charakterizace stereoizomerů peptidů a pseudopeptidů kapilární elektroforézou

Capillary zone electrophoresis has been applied to separation of diastereomers of phosphinic pseudopeptides in achiral media, and to separation of enantiomers of antimicrobial dipeptide beta-alanyl-L,D-tyrosine in chiral media using beta-cyclodextrin as chiral selector

Analytical and preparative separations of biologically active peptides by capillary and free-flow electromigration methods

Combination of capillary and free-flow electromigration methods has been applied to qualitative and quantitative microanalysis and preparative purification of biologically active peptides

Capillary electrophoresis applied to chiral analysis of helquats and characterization of their intermediates and interconversion barriers using randomly and single isomer sulfated cyclodextrins as stereoselectors

Capillary electrophoresis in acidic sodium phosphate background electrolyte, pH 2.4, with randomly sulfated alfa-, beta- and gamma-cyclodextrins as chiral selectors was applied to fast, high-resolution separation of enantiomers of a series of 35 helquats, a new class of N-heteroaromatic dicationic helicene-like species. The developed methodology was employed for evaluation of preparative enantioresolution procedures of helquats, for monitoring their racemization and for determination of interconversion barrier of helquat enantiomers

Capillary isotachophoresis and zone electrophoresis applied to determination of effective charge of polyelectrolytes

Capillary electromigration methods, isotachophoresis (CITP) and zone electrophoresis (CZE) were applied to determination of effective charge of poly-alpha-L-glutamic acid and poly-alpha-L-lysine using both CITP-dedicated device and common CZE apparatus. Combination of CITP and CZE methods in both these types of devices proved to be a suitable platform for determination of effective charge of a wide range of polyelectrolytes – weak and strong, polycations and polyanions