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Title: Thermodynamic study of an unusual chiral separation. Propranolol enantiomers on an immobilized cellulase

Abstract

The thermodynamics of interaction of (R)- and (S)-propranolol between an acetic acid buffer (pH = 4.7 and 5.5) and the protein cellobiohydrolase I immobilized on silica gel was studied between 5 and 45{degree}C. The equilibrium data were fitted to a biLangmuir adsorption isotherm with excellent agreement. One of the two Langmuir contributions is the same for both enantiomers and accounts for the nonspecific interactions between these compounds and most sites on the surfaces (type-I, nonselective sites). It has a large saturation capacity. The second contribution accounts for the chiral selective interactions (type-II sites). It has a lower monolayer capacity than the first. The interaction enthalpy and entropy on type-I sites are -1.1 kcal/mol and +0.1 cal/(mol K), respectively. For type-II sites, they are -1.9 kcal/mol and -2.6 cal/(mol K), respectively, for (R)-propranolol and +1.6 kcal/mol and +11.6 cal/(mol K), respectively, for (S)-propranolol at pH = 5.5. This explains why at this pH the retention time of the less-retained R enantiomer decreases with increasing temperature, while the retention time of the S enantiomer increases, causing a large increase of the separation factor when the temperature is raised from 5 to 45{degree}C. The saturation capacity of the chiral contributions depends strongly onmore » the pH, and the retention times of both enantiomers decrease with increasing temperature at pH = 4.7. 46 refs., 6 figs., 5 tabs.« less

Authors:
; ;  [1]
  1. Univ. of Tennessee, Knoxville, TN (United States)|[Oak Ridge National Lab., TN (United States)
Publication Date:
OSTI Identifier:
466322
Resource Type:
Journal Article
Resource Relation:
Journal Name: Journal of the American Chemical Society; Journal Volume: 119; Journal Issue: 6; Other Information: PBD: 12 Feb 1997
Country of Publication:
United States
Language:
English
Subject:
40 CHEMISTRY; 55 BIOLOGY AND MEDICINE, BASIC STUDIES; ALCOHOLS; SEPARATION PROCESSES; ISOMERS; CHEMICAL REACTIONS; THERMODYNAMICS; ADSORPTION; TEMPERATURE DEPENDENCE; PH VALUE; EXPERIMENTAL DATA

Citation Formats

Fornstedt, T., Sajonz, P., and Guiochon, G. Thermodynamic study of an unusual chiral separation. Propranolol enantiomers on an immobilized cellulase. United States: N. p., 1997. Web. doi:10.1021/ja9631458.
Fornstedt, T., Sajonz, P., & Guiochon, G. Thermodynamic study of an unusual chiral separation. Propranolol enantiomers on an immobilized cellulase. United States. doi:10.1021/ja9631458.
Fornstedt, T., Sajonz, P., and Guiochon, G. Wed . "Thermodynamic study of an unusual chiral separation. Propranolol enantiomers on an immobilized cellulase". United States. doi:10.1021/ja9631458.
@article{osti_466322,
title = {Thermodynamic study of an unusual chiral separation. Propranolol enantiomers on an immobilized cellulase},
author = {Fornstedt, T. and Sajonz, P. and Guiochon, G.},
abstractNote = {The thermodynamics of interaction of (R)- and (S)-propranolol between an acetic acid buffer (pH = 4.7 and 5.5) and the protein cellobiohydrolase I immobilized on silica gel was studied between 5 and 45{degree}C. The equilibrium data were fitted to a biLangmuir adsorption isotherm with excellent agreement. One of the two Langmuir contributions is the same for both enantiomers and accounts for the nonspecific interactions between these compounds and most sites on the surfaces (type-I, nonselective sites). It has a large saturation capacity. The second contribution accounts for the chiral selective interactions (type-II sites). It has a lower monolayer capacity than the first. The interaction enthalpy and entropy on type-I sites are -1.1 kcal/mol and +0.1 cal/(mol K), respectively. For type-II sites, they are -1.9 kcal/mol and -2.6 cal/(mol K), respectively, for (R)-propranolol and +1.6 kcal/mol and +11.6 cal/(mol K), respectively, for (S)-propranolol at pH = 5.5. This explains why at this pH the retention time of the less-retained R enantiomer decreases with increasing temperature, while the retention time of the S enantiomer increases, causing a large increase of the separation factor when the temperature is raised from 5 to 45{degree}C. The saturation capacity of the chiral contributions depends strongly on the pH, and the retention times of both enantiomers decrease with increasing temperature at pH = 4.7. 46 refs., 6 figs., 5 tabs.},
doi = {10.1021/ja9631458},
journal = {Journal of the American Chemical Society},
number = 6,
volume = 119,
place = {United States},
year = {Wed Feb 12 00:00:00 EST 1997},
month = {Wed Feb 12 00:00:00 EST 1997}
}
  • The authors reported previously on the unusual thermodynamic characteristics of the enantioselective interactions between the enantiomers of the {beta}-blocker propranolol and the protein cellobiohydrolase I immobilized on silica. The adsorption of the more retained enantiomer, (S)-propranolol, is endothermic while that of the (R)-propranolol is exothermic. This causes a rapid increase of the selectivity factor with increasing temperature. In this work, the complex dependence of the selectivity factor on the pH of the solvent is studied. They determined the equilibrium isotherms of (R)- and (S)-propranolol in a wide concentration range (0.25 {micro}M to 1.1 mM) at six different mobile-phase pHs (4.7,more » 5.0, 5.2, 5.5, 5.7, and 6.0) and fitted the data obtained to the bi-Langmuir model. This gave the saturation capacity and the binding constant of the nonselective contribution for the two enantiomers. It also gave these parameters for the enantioselective contributions of each of them. The dependence of these parameters on the pH is discussed and interpreted in terms of the retention mechanism. Conclusions are in excellent agreement with recent, independent results on the structure of the protein obtained by X-ray crystallography.« less
  • The thermodynamics and mass transfer kinetics of the retention of the R and S enantiomers of propranolol were investigated on a system comprising an acetic acid buffer solution as mobile phase and the protein cellobiohydrolase I immobilized on silica as the stationary phase. The bi-Langmuir isotherm model fitted best to each set of single-component isotherm data. The monolayer capacity of the nonchiral type of adsorption sites was 22.9 mM. For the chiral type of sites, it was 0.24 mM for the R enantiomer and 0.64 nM for the S enantiomer. Peak tailing was observed, even at very low concentrations allowingmore » operation of the low-capacity chiral sites under linear conditions. This tailing can be explained on the basis of heterogeneous mass transfer kinetics. At higher concentrations, which are often used in analytical applications, the isotherms on the chiral sites no longer have a linear behavior, and peak tailing is consequently more pronounced. Under those conditions, peak tailing originates from the combined effect of heterogeneous thermodynamics and heterogeneous mass transfer kinetics. These complex phenomena are explained and modeled using the transport-dispersive model with a solid film linear driving force model modified to account for heterogeneous mass transfer kinetics. The rate coefficient of the mass transfer kinetics was found to be concentration dependent. 36 refs., 5 figs., 1 tab.« less
  • The retention and the separation of the enantiomers of 1-phenylpropanol (1PP), 2-phenylpropanol (2PP), and 3-chloro-1-phenylpropanol (3CPP) on silica-bonded quinidine carbamate under normal phase HPLC conditions were investigated. A relatively high selectivity of the stationary phase for 3CPP and 1PP ({alpha} {approx} 1.07-1.09) was achieved with eluents containing ethyl acetate as the polar modifier. These mobile phases were examined in detail. Based on the set of chromatographic and thermodynamic data collected, conclusions regarding the mechanism of enantioselectivity and the structure of the selector chiral center are made.
  • The LC separation of 13 enantiomeric pairs of ferrocene, ruthenocene, and osmocene analogues is described. Recently developed ..beta..-cyclodextrin bonded columns, which contain no interfering nitrogen or sulfur linkages, are particularly well suited to the separation of these compounds. The effect of solute structure and size on resolution and separation efficiency is examined. Both the application of this system and the mechanism of separation are discussed. 33 references, 3 figures, 1 table.