A molecular chromatographic approach to analyze the cell diffusion of arginase inhibitors.

Our group demonstrated that arginase inhibition reduces endothelial dysfunction in spontaneously hypertensive rats [C. Demougeot, A. Prigent-Tessier, C.

Association mechanism of four acetylcholinesterase inhibitors (AChEIs) with human serum albumin: a biochromatographic approach.

In this work, the interaction of a series of acetylcholinesterase inhibitors (AChEIs; donepezil, galanthamine, huperzine and neostigmine) with human serum albumin (HSA) immobilized on porous silica particles was studied using a biochromatographic approach. For all the tested AChEI molecules, linear retention plots were observed at all temperatures. An analysis of the thermodynamics (i.

Reanalysis of the testosterone displacement from its HSA binding site by DHEA using competitive Langmuir isotherm.

In a previous manuscript [C. Andre, A. Berthelot, J.

Thermodynamic approach for studying both the retention and complexation mechanisms with hydroxy-propyl-beta-cyclodextrin of a phenoxy-propionic acid herbicide series.

The retention and complexation mechanisms of a herbicide series were studied from a chromatographic approach using a novel column called "Nautilus((R))". The effects of water fraction and the hydroxy-propyl-beta-cyclodextrin (HP-beta-CD) concentration in the mobile phase were analysed in relation to the column temperature. Two retention models of phenoxy-propionic acid (PPA) derivatives were investigated.

Chiral discrimination of phenoxypropionic acid herbicide enantiomers on teicoplanin phase: methanol dependence and eluent pH consideration.

The chiral recognition mechanism for a series of d,l phenoxypropionic acid herbicides (PPAs) on a teicoplanin stationary phase was investigated in reversed phase liquid chromatography (RPLC) over a wide range of mobile phase pH and column temperature. The effect of methanol on the enantiomeric separation was studied by varying its fraction (v/v) in the mobile phase. The thermodynamic data indicated that the chiral recognition was controlled by the interaction between the anionic form of the solute and the teicoplanin phase while those with the neutral form played a minor role.

Immobilization of arginase and its application in an enzymatic chromatographic column: thermodynamic studies of nor-NOHA/arginase binding and role of the reactive histidine residue.

A biochromatographic approach is developed to measure for the first time changes in enthalpy, heat capacity change and protonation for the binding of nor-NOHA to arginase in a wide temperature range. For this, the arginase enzyme was immobilized on a chromatographic support. It was established that this novel arginase column was stable during an extended period of time.

A humic acid stationary phase for the high performance liquid chromatography separation of buckminsterfullerenes: theoretical and practical aspects.

The influence of the mobile phase composition and column temperature on the chromatographic separation of five buckminsterfullerenes (C60, C70, C76, C78, C84) on a stationary phase based on silica gel with chemically bonded humic acid (Bonded humic acid column (BHAC)) was studied. The retention behavior of the fullerenes was measured under isocratic conditions with different mobile phase compositions, ranging from 0.05-0.

A novel cyclic hexapeptide as chiral selector: Application for HPLC separation of a series of dansyl amino and arylalkanoic acids.

In this paper, the synthesis of a cyclic hexapeptide molecule was presented and evaluated for the enantiomer separation of a series of dansyl amino and arylalkanoic acids using high performance liquid chromatography (HPLC). It was clearly vizualized that this chiral selector allowed the separation of a great number of enantiomer pairs. The influences of the size and the hydrogen bonding donor (HBD) parameter of the organic modifier (OM) (THF (HBD=0.

Enantioselective aptameric molecular recognition material: Design of a novel chiral stationary phase for enantioseparation of a series of chiral herbicides by capillary electrochromatography.

A chiral stationary phase derived from an L-RNA aptamer is evaluated for the enantiomer separation of a series of herbicide molecules (aryloxypropionic, aryloxyphenoxypropionic, and aminopropionic acid) by CEC after binding to biotin and grafting upon streptavidin-modified porous glass beads. We demonstrated that the aptamer capillary was stable in term of efficiency and retention during a long period. The influences of the mobile phase constitution and its flow-velocity on the enantioseparation were also investigated.

Association mechanism between a series of rodenticide and humic acid: a frontal analysis to support the biological data.

The binding constants (K) of a series of anticoagulant rodenticides with the main soil organic component, humic acid (HA), were determined using frontal analysis approach. The order of the binding constants was identical as the one obtained in a previous paper [J. Chromatogr.

Testimony of the correlation between DHEA and bioavailable testosterone using a biochromatographic concept: effect of two salts.

In a previous paper (C. André et al., submitted to J.

A biochromatographic framework to evaluate the calcium effect on the antihypertensive molecule-human serum albumin binding.

The Ca(2+) cation effect on the antihypertensive molecule binding on human serum albumin (HSA) was studied by biochromatography. The thermodynamic parameters corresponding to this binding were determined for a wide range of Ca(2+) concentration (x). For the two antihypertensive molecules under study, their binding to HSA can be divided into two Ca(2+) cation concentration regions due to a HSA phase transition.

Supercoiled circular DNA retention in nonequilibrium chromatography: viscosity and velocity dependence--behavior difference with proteins.

This study demonstrates that the retention behavior of various circular double-stranded DNA molecules (3, 5, and 10 kb) increases over the entire flow-rate range (0.02-1.8 mL/min) at all the mobile phase viscosities (h).

Concentration of sodium ion as the determining factor for the association of dansyl amino acids with the teicoplanin molecule in reversed-phase liquid chromatography.

The mechanism of the binding of D,L dansyl amino acids to teicoplanin was investigated. Na+ was used as an indicator of the interactions between the solutes and teicoplanin. The number (n) of sodium ions, Na+, excluded from the solute-teicoplanin interface when analyte transfer occurred was determined.

Triazine-human serum albumin association: thermodynamic approach and sodium effect.

Human serum albumin (HSA) serves as a carrier protein to transport triazine herbicides to molecular targets. In this paper, a theoretical treatment was developed to describe the HSA-triazine herbicides association. A determination of the association constant, K, as well as the degree of complexation n(c) (the percent of complex guest) was carried out.

Role of the Na+ ion on phenol derivatives/hydroxypropyl-beta-cyclodextrin complex formation on porous graphitic carbon phase.

The reversed-phase liquid chromatography retention of phenol derivatives was investigated over a concentration range of sodium chloride (0-10(-2) M) and hydroxypropyl-beta-cyclodextrin (HP-beta-CD) (0-35x10(-3) M) using a porous graphitic carbon (PGC) stationary phase and a methanol/water mixture (50:50 (v/v)) as the mobile phase. A theoretical treatment was developed to investigate the effect of the sodium chloride and hydroxypropyl-beta-cyclodextrin on the equilibrium between the solutes with the PGC surface and the aqueous medium, respectively. The thermodynamic parameter variations were calculated using van't Hoff plots.

Supercoiled circular DNA and protein retention in non-equilibrium chromatography temperature and velocity dependence: testimony of a transition.

Non-equilibrium chromatography (NEC) is a chromatographic mode for the rapid separation of polymers. The retention behavior of various proteins (human, chicken, bovine serum albumin) and supercoiled circular double-stranded DNA (plasmids) was investigated using a phosphate buffer as a mobile phase at different velocities and column temperatures with a C1 column with very low-packing particle diameter as a stationary phase. It was shown that the two factors (temperature and velocity) constituted important parameters in the retention mechanism of plasmids and proteins in NEC.