1
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Studies on the retention mechanism of solutes in hydrophilic interaction chromatography using stoichiometric displacement theory I. The linear relationship of lgk' vs. lg[H2O]. Talanta 2018; 176:499-508. [DOI: 10.1016/j.talanta.2017.08.062] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/18/2017] [Revised: 08/11/2017] [Accepted: 08/18/2017] [Indexed: 01/26/2023]
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2
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Bian M, Tian L, Yao C. An improved method of simultaneous determination of four bioactive compounds in Evodiae Fructus using ionic liquids as mobile phase additives in high performance liquid chromatography. Chem Res Chin Univ 2017. [DOI: 10.1007/s40242-017-6434-1] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/19/2022]
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3
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Kulsing C, Komaromy AZ, Boysen RI, Hearn MTW. On-line determination by small angle X-ray scattering of the shape of hen egg white lysozyme immediately following elution from a hydrophobic interaction chromatography column. Analyst 2016; 141:5810-5814. [DOI: 10.1039/c6an00851h] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
This study documents the use of an integrated approach, involving on-line HIC interfaced with SAXS measurements, to monitor the conformational status of proteins immediately upon elution from a chromatographic column.
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Affiliation(s)
- Chadin Kulsing
- Australian Research Council Special Research Centre for Green Chemistry
- Australian Centre for Research on Separation Science (ACROSS)
- Monash University
- Melbourne
- Australia
| | - Andras Z. Komaromy
- Australian Research Council Special Research Centre for Green Chemistry
- Australian Centre for Research on Separation Science (ACROSS)
- Monash University
- Melbourne
- Australia
| | - Reinhard I. Boysen
- Australian Research Council Special Research Centre for Green Chemistry
- Australian Centre for Research on Separation Science (ACROSS)
- Monash University
- Melbourne
- Australia
| | - Milton T. W. Hearn
- Australian Research Council Special Research Centre for Green Chemistry
- Australian Centre for Research on Separation Science (ACROSS)
- Monash University
- Melbourne
- Australia
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4
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Deitcher R, O’Connell J, Fernandez E. Changes in solvent exposure reveal the kinetics and equilibria of adsorbed protein unfolding in hydrophobic interaction chromatography. J Chromatogr A 2010; 1217:5571-83. [PMID: 20630532 PMCID: PMC2956115 DOI: 10.1016/j.chroma.2010.06.051] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/06/2010] [Revised: 06/14/2010] [Accepted: 06/18/2010] [Indexed: 11/17/2022]
Abstract
Hydrogen exchange has been a useful technique for studying the conformational state of proteins, both in bulk solution and at interfaces, for several decades. Here, we propose a physically based model of simultaneous protein adsorption, unfolding and hydrogen exchange in HIC. An accompanying experimental protocol, utilizing mass spectrometry to quantify deuterium labeling, enables the determination of both the equilibrium partitioning between conformational states and pseudo-first order rate constants for folding and unfolding of adsorbed protein. Unlike chromatographic techniques, which rely on the interpretation of bulk phase behavior, this methodology utilizes the measurement of a molecular property (solvent exposure) and provides insight into the nature of the unfolded conformation in the adsorbed phase. Three model proteins of varying conformational stability, alpha-chymotrypsinogen A, beta-lactoglobulin B, and holo alpha-lactalbumin, are studied on Sepharose HIC resins possessing assorted ligand chemistries and densities. alpha-Chymotrypsinogen, conformationally the most stable protein in the set, exhibits no change in solvent exposure at all the conditions studied, even when isocratic pulse-response chromatography suggests nearly irreversible adsorption. Apparent unfolding energies of adsorbed beta-lactoglobulin B and holo alpha-lactalbumin range from -4 to 3 kJ/mol and are dependent on resin properties and salt concentration. Characteristic pseudo-first order rate constants for surface-induced unfolding are 0.2-0.9 min(-1). While poor protein recovery in HIC is often associated with irreversible unfolding, this study documents that non-eluting behavior can occur when surface unfolding is reversible or does not occur at all. Further, this hydrogen exchange technique can be used to assess the conformation of adsorbed protein under conditions where the protein is non-eluting and chromatographic methods are not applicable.
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Affiliation(s)
- R.W. Deitcher
- Department of Chemical Engineering, University of Virginia, Charlottesville, VA, USA 22904-4741
| | - J.P. O’Connell
- Department of Chemical Engineering, University of Virginia, Charlottesville, VA, USA 22904-4741
| | - E.J. Fernandez
- Department of Chemical Engineering, University of Virginia, Charlottesville, VA, USA 22904-4741
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5
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Hearn MTW, Anspach B. CHEMICAL, PHYSICAL, AND BIOCHEMICAL CONCEPTS IN ISOLATION AND PURIFICATION OF PROTEINS*. ACTA ACUST UNITED AC 2007. [DOI: 10.1081/spm-100108160] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/03/2022]
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6
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Sawicka K, Sahota T, Taylor MJ, Tanna S. Development of a reversed-phase high-performance liquid chromatography method for the analysis of components from a closed-loop insulin delivery system. J Chromatogr A 2006; 1132:117-23. [PMID: 16901496 DOI: 10.1016/j.chroma.2006.07.053] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/23/2006] [Revised: 07/11/2006] [Accepted: 07/25/2006] [Indexed: 11/30/2022]
Abstract
A reversed-phase HPLC method has been developed which enables separation of the three components of a closed-loop insulin delivery system, namely concanavalin A methacrylamide (Con A-MA), dextran methacrylate (Dex-MA) and bovine insulin. The analysis of Con A-MA represents a significant challenge due to the formation of multiple conformations on contact with the chromatographic surface and the mobile phase. The extent of conformational change is shown to be dependent on a number of parameters: column temperature, mobile phase pH, contact time with the chromatographic surface, salt type and concentration and the organic modifier. By manipulation of these variables, protein denaturation can be minimised and recovery improved.
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Affiliation(s)
- Kirsty Sawicka
- Leicester School of Pharmacy, Faculty of Health and Life Sciences, De Montfort University, The Gateway, Leicester LE1 9BH, UK
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7
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Xiao Y, Freed AS, Jones TT, Makrodimitris K, O'Connell JP, Fernandez EJ. Protein instability during HIC: describing the effects of mobile phase conditions on instability and chromatographic retention. Biotechnol Bioeng 2006; 93:1177-89. [PMID: 16444741 DOI: 10.1002/bit.20826] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022]
Abstract
Hydrophobic interaction chromatography (HIC) is known to be potentially denaturing to proteins, but the effects of mobile phase conditions on chromatographic behavior are not well understood. In this study, we apply a model describing the effects of secondary protein unfolding equilibrium on chromatographic behavior, including the effects of salt concentration on both stability and adsorption. We use alpha-lactalbumin as a model protein that in the presence and absence of calcium, allows evaluation of adsorption parameters for folded and unfolded species independently. The HIC adsorption equilibrium under linear binding conditions and solution phase protein stability have been obtained from a combination of literature and new experiments. The effect of salt concentration on protein stability and the rate constant for unfolding on the chromatographic surface have been determined by fitting the model to isocratic chromatography data under marginally stable conditions. The model successfully describes the effects of added calcium and ammonium sulfate. The results demonstrate the importance of considering the effects on stability of mobile phase modifiers when applying HIC to marginally stable
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Affiliation(s)
- Yunzhi Xiao
- Department of Chemical Engineering, University of Virginia, 102 Engineers' Way, Charlottesville, 22904-4741, USA
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8
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Xiao Y, Jones TT, Laurent AH, O'Connell JP, Przybycien TM, Fernandez EJ. Protein instability during HIC: Hydrogen exchange labeling analysis and a framework for describing mobile and stationary phase effects. Biotechnol Bioeng 2006; 96:80-93. [PMID: 16952152 DOI: 10.1002/bit.21186] [Citation(s) in RCA: 32] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
Abstract
Unfolding of marginally stable proteins is a significant factor in commercial application of hydrophobic interaction chromatography (HIC). In this work, hydrogen-deuterium isotope exchange labeling has been used to monitor protein unfolding on HIC media for different stationary phase hydrophobicities and as a function of ammonium sulfate concentration. Circular dichroism and Raman spectroscopy were also used to characterize the structural perturbations experienced by solution phase protein that had been exposed to media and by protein adsorbed on media. As expected, greater instability is seen on chromatographic media with greater apparent hydrophobicity. However, increased salt concentrations also led to more unfolding, despite the well-known stabilizing effect of ammonium sulfate in solution. A thermodynamic framework is proposed to account for the effects of salt on both adsorption and stability during hydrophobic chromatography. Using appropriate estimates of input quantities, analysis with the framework can explain how salt effects on stability in chromatographic systems may contrast with solution stability.
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Affiliation(s)
- Yunzhi Xiao
- Department of Chemical Engineering, University of Virginia, 102 Engineers' Way, Charlottesville, VA 22904-4741, USA
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9
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Chen SH, Li CW. Thermodynamic studies of pressure-induced retention of peptides in reversed-phase liquid chromatography. J Chromatogr A 2004; 1023:41-7. [PMID: 14760848 DOI: 10.1016/j.chroma.2003.09.057] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
Abstract
The pressure-induced retention of peptides on reversed-phase HPLC was studied by systematically changing organic solvent composition and temperature at both low (19 bar) and high (318 bar) pressures using a homologous series of hydrophobic poly-L-phenylalanine (n = 2-7) as the model compound. Based on van' t Hoff plots under different organic solvent compositions and pressures, the enthalpy change for the solute (deltaH) was determined. Moreover, both the enthalpy and entropy change for each phenylalanine residue (deltadeltaH and deltadeltaS), which corresponds to solute retention on a microenvironment along the depth of C18 chain, were also calculated by direct subtractions. Results indicate that under acetonitrile (ACN) compositions above 35%, the pressure caused deltadeltaS value to change from a negative to a positive value and both deltaH and deltadeltaH to change from a negative to a less negative value, all leading to a thermodynamic state closer to those under 35% acetonitrile composition. This implies that the pressure-induced retention observed in this study was an entropy-favored but enthalpy-unfavored process and was explained by pressure-induced desorption of solvent molecules that were associated with the stationary phase or with the peptide solute. Under 35% acetonitrile composition, however, it was found that neither deltadeltaH nor deltadeltaS value was significantly changed by the pressure. Whereas, both deltaH value and the intercept of van't Hoff plots under 35% acetonitrile composition were increased by pressure. This indicates that under low organic solvent composition, 35%, most of the acetonitrile molecules adsorbed on the surface of the stationary phase and only little solvent molecules were dissolved in the bulk stationary phase where the phenylalanine residues were partitioned. This study has provided new thermodynamic insights to the pressure-induced retention for peptides and proteins.
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Affiliation(s)
- Shu-Hui Chen
- Department of Chemistry, National Cheng Kung University, Tainan 701, Taiwan.
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10
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Li L, Thompson R, Sowa JR, Clausen A, Dowling T. Kinetic study on the epimerization of trityloxymethyl butyrolactol by liquid chromatography. J Chromatogr A 2004; 1043:171-5. [PMID: 15330090 DOI: 10.1016/j.chroma.2004.05.068] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
The epimerization of trityloxymethyl butyrolactol has been investigated using dynamic chromatography and an approximation function introduced by Trapp and Schurig that is based on stochastic and theoretical plate models. The epimerization rate constants and Gibbs activation energies of epimerization are directly calculated from chromatographic peak parameters, i.e. retention times of the interconverting species, peak width at half height and the relative plateau height by using the approximation function. The relationships between peak shape and chromatographic conditions, such as flow-rate, temperature and pH are investigated.
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Affiliation(s)
- L Li
- Analytical Research Department, Merck Research Laboratory, Rahway, NJ 07065-0900, USA.
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11
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Lim DSW, Kuo JS, Chiu DT. Parametric investigation on the effect of channel topologies on electrophoretic separations. J Chromatogr A 2004; 1027:237-44. [PMID: 14971508 DOI: 10.1016/j.chroma.2003.09.019] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
Abstract
This paper presents a systematic study that illustrates the importance of the topologies of microchannels on electrokinetically based separation. Using theoretical and numerical analyses, we designed and showed that topologies that significantly increased the surface-to-volume ratio of the channel can provide dramatic improvement in the ability of the channel both to dissipate the heat generated by Joule heating and to reduce the axial dispersion associated with the siphoning effect. The incremental benefit and tradeoff of geometric complexity was also evaluated. The improvement offered by topographically patterned channels, such as finned structures, is especially pertinent in the development of preparative or semi-preparative scale electrokinetically driven separations, such as capillary electrophoresis and capillary electrochromatography, in which large cross sections of channels are required to achieve the needed volumetric throughput.
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Affiliation(s)
- David S W Lim
- Department of Chemistry, University of Washington, Seattle, WA 98195-1700, USA
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12
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Oswald P, Desmet K, Sandra P, Krupcik J, Armstrong DW. Evaluation of reversible and irreversible models for the determination of the enantiomerization energy barrier for N-(p-methoxybenzyl)-1,3,2-benzodithiazol-1-oxide by supercritical fluid chromatography. Chirality 2002; 14:334-9. [PMID: 11968075 DOI: 10.1002/chir.10077] [Citation(s) in RCA: 20] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
It has been found that the interconversion of enantiomers on a chromatographic column during the separation process can be studied by the first-order kinetic equations derived both for reversible and irreversible reactions in a stationary system if the extent of interconversion is not too high. The equation derived for irreversible reactions gives, however, results also for higher degrees of enantiomerization while that derived for reversible interconversion failed. The irreversible equation was used to determine the enantiomerization barrier of N-(p-methoxybenzyl)-l,3,2-benzodithiazol-l-oxide enantiomers by supercritical fluid chromatography. The racemate of N-(p-methoxybenzyl)-l,3,2-benzodithiazol-l-oxide was separated by supercritical fluid chromatography on the (R,R)-Whelk-Ol column with supercritical carbon dioxide containing 20% methanol as a mobile phase. Peak areas of enantiomers prior to and after the separation used for the calculation of the enantiomerization barrier were determined by computer-assisted peak deconvolution of peak clusters registered on chromatograms using commercial software.
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Affiliation(s)
- P Oswald
- Department of Analytical Chemistry, Slovak University of Technology, Bratislava 81237, Slovakia
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13
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Recent developments of the stoichiometric displacement model for separation processes. ACTA ACUST UNITED AC 2001. [DOI: 10.1007/bf02900546] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/22/2022]
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14
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Righetti PG, Verzola B. Folding/unfolding/refolding of proteins: present methodologies in comparison with capillary zone electrophoresis. Electrophoresis 2001; 22:2359-74. [PMID: 11519938 DOI: 10.1002/1522-2683(200107)22:12<2359::aid-elps2359>3.0.co;2-8] [Citation(s) in RCA: 41] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022]
Abstract
A series of techniques for monitoring protein folding/unfolding/misfolding equilibria are here assessed and compared with capillary zone electrophoresis (CZE). They include spectroscopic techniques, such as circular dichroism, intrinsic fluorescence, nuclear magnetic resonance, Fourier transform infrared and Raman spectroscopy, small-angle X-ray scattering, as well as techniques based on biological assays, such as limited proteolysis and immunochemical analysis of different conformational states. Some unusual probes, such as mass spectrometry for probing unfolding transitions, are also discussed. Size-exclusion chromatography is also evaluated in view of the fact that this technique, like all electrophoretic techniques, and unlike spectroscopic probes, which can only see an average signal in mixed populations, can indeed physically separate folded vs. unfolded macromolecules, especially in the case of slow equilibria. Particular emphasis is devoted to electrophoretic techniques, such as gel-slab electrophoresis in transverse urea or thermal gradients, and CZE. In the latter case, a number of applications are shown, demonstrating the excellent correlation of CZE with more traditional probes, such as intrinsic fluorescence monitoring. It is additionally shown that CZE can be used for measuring the deltaG degrees of unfolding over the pH scale, in good agreement with theoretical calculations on the electrostatic free energy of folding vs. pH, as calculated with a linearized Poisson-Boltzmann equation. Finally, it is demonstrated that CZE can probe also aggregate formation in the presence of helix-inducing agents, such as trifluorethanol.
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Affiliation(s)
- P G Righetti
- University of Verona, Department of Agricultural and Industrial Biotechnologies, Italy.
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15
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Mariott P, Trapp O, Shellie R, Schurig VG. Time-resolved cryogenic modulation reveals isomer interconversion profiles in dynamic chromatography. J Chromatogr A 2001; 919:115-26. [PMID: 11459297 DOI: 10.1016/s0021-9673(01)00778-6] [Citation(s) in RCA: 32] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
The dynamic chromatographic study of interconversion of E and Z forms of oximes has been investigated by using a novel cryogenic modulation method in a two-dimensional gas chromatographic array. The primary column is a conventional capillary GC column on which the molecular interconversion proceeds. In this case, the molecular dynamical process leads to a peak profile describing the kinetics and thermodynamics of the interconverting molecules during its chromatographic elution. Thus an interconversion region intercedes the elution of the individual stereoisomers of the reaction. Since the molecules are isomers, classical molecular identification methods such as gas chromatography-mass spectrometry are unable to study the individual instantaneous amounts of each of the compounds. Hence the infinitesimal profiles of interconversion along the entire column have never been experimentally observed; rather the total profile is normally subjected to mathematical modelling studies in order to match experiment with theory, and to gain the kinetic parameters of the process. In the present study, an instantaneous ratio of the individual isomers can be found during the chromatographic elution by direct measurement. This is achieved by using a cryogenic zone focussing process, with rapid longitudinal modulation of a cold trap and continual pulsing of collected zones into a fast-analysis high-resolution capillary column on which isomer interconversion is minimized. The data can be displayed as a two-dimensional contour plot to demonstrate the individual isomer profiles. The two-dimensional analysis also allows easy measurement of the peak ratios of the two isomers which is an indicator of the extent of interconversion that has taken place. Two model systems, acetaldoxime and butyraldoxime, were chosen to illustrate the use of the cryogenic modulation procedure. It is anticipated that the procedure could be applied to other molecules which exhibit gas-phase isomerizations or reactions.
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Affiliation(s)
- P Mariott
- Chromatography and Molecular Separations Group, Royal Melbourne Institute of Technology, Victoria, Australia.
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16
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Chen SH, Ho CT, Hsiao KY, Chen JM. Pressure-induced retention of the lysozyme on reversed-phase liquid chromatography. J Chromatogr A 2000; 891:207-15. [PMID: 11043781 DOI: 10.1016/s0021-9673(00)00638-5] [Citation(s) in RCA: 33] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/18/2022]
Abstract
This study investigated the effect of pressure on the retention behavior of a model protein, lysozyme, on octadecylsilica (C18) stationary phase under various equilibrium conditions. It is demonstrated that the retention time of the lysozyme was increased by as much as two to three times as the absolute pressure on the viewing window was increased from 23 to 318 bar. This pressure-induced retention was likely to be reversible and the corresponding volume change (deltaV = Vsta - Vmob) was found to be on the order of minus tens to hundreds of mL/mol. Moreover, the pressure-induced retention was also observed for a homologous series of hydrophobic poly-L-phenylalanine, which do not have the secondary structure, and the volume change was determined to be around minus 10 mL/mol per phenylalanine. Perturbations in solute ionization and conformational change are predicted to have a minor impact under the investigated conditions. It is believed that the pressure-induced shift of the equilibria regarding hydrophobic ad-desorption is the major cause of the observed increase of protein retention. About ten phenylalanine-equivalent residues on the lysozyme surface were involved in the hydrophobic association with the chromatographic ligands.
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Affiliation(s)
- S H Chen
- Department of Chemistry, National Cheng Kung University, Tainan, Taiwan.
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17
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Hearn MT. Physicochemical factors in polypeptide and protein purification and analysis by high-performance liquid chromatographic techniques: current status and challenges for the future. HANDBOOK OF BIOSEPARATIONS 2000. [DOI: 10.1016/s0149-6395(00)80050-1] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/24/2022]
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18
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de Frutos M, Cifuentes A, Díez-Masa JC, Camafeita E, Méndez E. Multiple Peaks in HPLC of Proteins: Bovine Serum Albumin Eluted in a Reversed-Phase System. ACTA ACUST UNITED AC 1998. [DOI: 10.1002/(sici)1521-4168(19980101)21:1<18::aid-jhrc18>3.0.co;2-5] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
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19
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Sadana A. Protein Inactivations During Chromatographic Methods of Separation. SEP SCI TECHNOL 1998. [DOI: 10.1016/s0149-6395(98)80033-0] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
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20
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Aguilar MI, Hearn MT. High-resolution reversed-phase high-performance liquid chromatography of peptides and proteins. Methods Enzymol 1996; 270:3-26. [PMID: 8803962 DOI: 10.1016/s0076-6879(96)70003-4] [Citation(s) in RCA: 52] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/02/2023]
Affiliation(s)
- M I Aguilar
- Department of Biochemistry, Monash University, Clayton, Victoria, Australia
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21
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Jensen WA, Armstrong JM, De Giorgio J, Hearn MT. Stability studies on maize leaf phosphoenolpyruvate carboxylase: the effect of salts. Biochemistry 1995; 34:472-80. [PMID: 7819239 DOI: 10.1021/bi00002a011] [Citation(s) in RCA: 18] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/27/2023]
Abstract
The solution stability of phosphoenolpyruvate carboxylase (PEPC) has been determined in the presence of various salts by temperature-accelerated enzyme inactivation and also by using high-performance size-exclusion chromatography. Kosmotropic (water structuring) anions in the Hofmeister series (HPO(4)2-, citrate3-, SO(4)2-, F-, OAc-) and glutamate stabilized the enzyme most effectively, while Cl- (a borderline Hofmeister anion) and Br- (a chaotropic anion) were destabilizing. The effects of the cations on PEPC stability ranged from relatively inert (Na+, K+) to destabilizing ((CH3)4N+, NH4+, Li+). The observed stabilization of PEPC by specific salts has been interpreted in terms of the positive surface tension increment and the water-structuring effects conferred on the solution by the specific stabilizing reagents. Both these effects enhance hydrophobic interactions of proteins and increase the energy required to enlarge the surface area of the solvent cavity in which the protein resides. The destabilization of PEPC by some salts at a concentration of 0.5 M was associated with the dissociation of the tetrameric enzyme into its dimeric and monomeric forms, a process most probably occurring as a result of ion-peptide dipole binding, which promotes protein-solvent interaction and a subsequent reduction in the free energy of cavity formation. The stabilization of enzyme activity by kosmotropic salts depended on the salt concentration with maximum stabilization of PEPC in solution at 52 degrees C observed with 0.6-0.8 M sodium glutamate, 2 M KF, and 2.2 M KOAc. Higher concentrations of these salts resulted in decreased activity. This reduction in activity of PEPC in the presence of high concentrations of kosmotropic salts appears to be associated with irreversible conformational changes of the tetrameric enzyme.
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Affiliation(s)
- W A Jensen
- Department of Biochemistry, Monash University, Clayton, Victoria, Australia
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22
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Macášek F. Separation methods for chemical speciation of radionuclides and metals in environmental matrices. J Radioanal Nucl Chem 1994. [DOI: 10.1007/bf02043111] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/25/2022]
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23
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A comparative study of the retention behaviour and stability of cytochrome c in reversed-phase high-performance liquid chromatography. J Chromatogr A 1994. [DOI: 10.1016/0021-9673(94)00092-1] [Citation(s) in RCA: 21] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
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24
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Effect of protein conformation on experimental bandwidths in reversed-phase high-performance liquid chromatography. J Chromatogr A 1994. [DOI: 10.1016/0021-9673(94)80453-2] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
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25
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26
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Hossain M, Do D. The effects of denaturation in the displacement chromatographic behaviour of proteins. ACTA ACUST UNITED AC 1992. [DOI: 10.1016/0300-9467(92)80055-f] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
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27
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Monger LS, Olliff CJ. Reversed-phase chromatographic behaviour of beta-endorphin: evidence of conformational change. J Chromatogr A 1992; 595:125-35. [PMID: 1577905 DOI: 10.1016/0021-9673(92)85153-k] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/27/2022]
Abstract
The effect of alteration in isocratic mobile phase constituents, composition of sample solution, flow-rate and column temperature on the reversed-phase chromatographic behaviour of beta-endorphin was investigated. Beta-Endorphin was shown to be particularly sensitive to the concentration of organic modifier within the mobile phase. The relative contact area of beta-endorphin was demonstrated to be less than that of the much smaller molecule, gamma-endorphin, indicating that beta-endorphin is in a folded form under the mobile phase conditions utilised. Buffer molarity and pH were implicated in the conformational transition of beta-endorphin. In addition, the micro-environment of beta-endorphin prior to its injection onto the high-performance liquid chromatographic (HPLC) column is crucial to its chromatographic behaviour. Manipulation of the sample solvent environment produced reversible conformational modifications ultimately resulting in asymmetric and even split peaks. This phenomenon was more clearly seen when altering HPLC flow-rate. Elevation of HPLC column temperature provided additional evidence of structural change in beta-endorphin, with further conformational forms of this molecule being observed at higher temperatures. This work suggests that the chromatography of beta-endorphin involves a complex mechanism of separation which cannot be adequately explained by the two-state model of kinetic processes.
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Affiliation(s)
- L S Monger
- Pharmaceutical Sciences Research Group, Brighton Polytechnic, E. Sussex, UK
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28
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Jeng CY, Langer SH. Reaction kinetics and kinetic processes in modern liquid chromatographic reactors. J Chromatogr A 1992. [DOI: 10.1016/0021-9673(92)80002-c] [Citation(s) in RCA: 28] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/18/2022]
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29
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Johnston A, Hearn M. High-performance liquid chromatography of amino acids, peptides and proteins. J Chromatogr A 1991. [DOI: 10.1016/s0021-9673(01)87143-0] [Citation(s) in RCA: 17] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
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30
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Lin SW, Oroszlan P, Karger BL. Effect of metal ions on the unfolding kinetics of alpha-lactalbumin on weakly hydrophobic surfaces. J Chromatogr A 1991; 536:17-30. [PMID: 2050763 DOI: 10.1016/s0021-9673(01)89233-5] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/30/2022]
Abstract
The effect of metal ion [Ca2+ and Zn(NH3)4(2+)] on the unfolding kinetics of bovine-alpha-lactalbumin (alpha-LACT) on a weakly hydrophobic chromatographic surface (ethyl polyether phase bonded on porous silica, C2 ether) has been studied using surface intrinsic fluorescence spectroscopy and liquid chromatography. Chromatographic results on the C2 ether phase revealed two peaks for alpha-LACT, the first being the folded and the second an unfolded conformation, as determined by fluorescence spectroscopy. The retention time for the second peak was found to depend on the specific metal additive in the mobile phase. Fluorescence studies showed a slow change in emission maximum from ca. 330 nm to 350 nm and a 5-fold increase in emission intensity for the adsorbed protein in the unfolded state. By following the fluorescence emission intensity at a given wavelength during the unfolding process, biphasic kinetics were observed with the kinetic constants depending on the specific metal-ion additive. In addition, solution refolding rates of the desorbed, unfolded species were measured and found to be consistent with literature refolding rate constants.
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Affiliation(s)
- S W Lin
- Barnett Institute, Northeastern University, Boston, MA 02115
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31
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Effects of temperature and flow rate on frontal and elution chromatography of aggregating systems. ACTA ACUST UNITED AC 1991. [DOI: 10.1016/0956-9618(91)80009-o] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022]
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32
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Haginaka J, Wakai J, Takahashi K, Yasuda H, Katagi T. Chiral separation of propranolol and its ester derivatives on an ovomucoid-bonded silica: Influence of pH, ionic strength and organic modifier on retention, enantioselectivity and enantiomeric elution order. Chromatographia 1990. [DOI: 10.1007/bf02261228] [Citation(s) in RCA: 51] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
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33
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Mal'tsev VG, Nasledov DG, Trushin SA, Tennikova TB, Vinogradova LV, Volokitina IN, Zgonnik VN, Belenkii BG. High-performance liquid chromatography of proteins on short capillary columns. ACTA ACUST UNITED AC 1990. [DOI: 10.1002/jhrc.1240130310] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022]
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34
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Abstract
A series of standard small globular proteins in different unfolded states was studied by gradient reversed-phase liquid chromatography. The retention parameters Z [slope of log capacity factor (k') vs. log molar concentration of organic modifier, 1-propanol, in the mobile phase] and log I (the value of log k' at 1 M 1-propanol) were derived from gradient retention data. Each protein in four different conformational states, i.e., folded, chromatographic surface-unfolded, urea-unfolded and disulfide-bridge reduced-unfolded, showed a variation of 10-fold in Z and up to 10(12)-fold in I values. For the different states of all the proteins studied, the order of Z and I values was as follows: folded much less than surface-unfolded less than urea-unfolded less than reduced-unfolded. The differences in the values of the coefficients suggest, in agreement with literature reports, that proteins with their disulfide bridges cleaved have the largest degree of unfolding. In addition, the Z and I values and solution refolding kinetics all suggest that chromatographic surface-unfolded proteins have a lower degree of unfolding than their urea-unfolded forms. It was also found that an additional chemical cross-link in lysozyme caused a significant decrease in the first-order rate constant of the surface-induced unfolding process.
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Affiliation(s)
- S W Lin
- Barnett Institute of Chemical Analysis, Northeastern University, Boston, MA 02115
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35
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Fales HM, Lloyd HA, Ferretti JA, Silverton JV, Davis DG, Kon H. Optical resolution of the α-tocopherol spiro dimer and demonstration of its fluxional nature. ACTA ACUST UNITED AC 1990. [DOI: 10.1039/p29900001005] [Citation(s) in RCA: 16] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
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36
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Bertolini J, Guthridge M, Hearn MT. Rapid chromatographic isolation and immunoblot characterization of immunoreactive fibroblast growth factor-related polypeptides from various tissues. JOURNAL OF CHROMATOGRAPHY 1989; 491:49-60. [PMID: 2793982 DOI: 10.1016/s0378-4347(00)82818-2] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/02/2023]
Abstract
Procedures to rapidly isolate fibroblast growth factor (FGF)-like activity from a number of tissue sources (lung, plasma, brain, ovary, corpus luteum, pituitary, chondrosarcoma) of bovine, porcine or rat origin are described. In addition, immunoblotting experiments using well characterized and specific rabbit polyclonal anti-fibroblast growth factor beta (anti-FGF-beta) sera have been performed. Besides documenting the first report of the isolation of FGF-beta from bovine lung and plasma, these studies provide evidence for the existence of higher-molecular-mass proteins with FGF-beta-like immunoreactivity. For example, in addition to new truncated forms of the acidic and basic FGF (FGF-alpha and FGF-beta), respectively, other higher-molecular-mass immunoreactive proteins were detected in bovine, pig and rat brain, and in rat chondrosarcoma. The tissue distribution of these immunoreactive proteins and their competitive inhibition characteristics mitigate against the possibility that the polyclonal antisera are cross-reacting non-specifically with common cellular proteins. Rather, the data suggest that the immunoblotting technique is either detecting other proteins structurally related to FGF-beta or alternatively FGF-beta is strongly bound to specific carrier proteins (e.g. heparan sulphate proteoglycan fragments) associated with their transport and recognition at the cellular level.
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Affiliation(s)
- J Bertolini
- Department of Biochemistry, Monash University, Clayton, Victoria Australia
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37
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Kurochkina LP, Kolomijtseva GYa. Isolation of modified histone H3 from ultraviolet-irradiated deoxyribonucleoprotein by reversed-phase high-performance liquid chromatography. Anal Biochem 1989; 178:88-92. [PMID: 2729584 DOI: 10.1016/0003-2697(89)90361-8] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/02/2023]
Abstract
A rapid reversed-phase high-performance liquid chromatography procedure for the isolation of histone H3 and/or of thymine modified at the lysine residue histone H3 from uv-irradiated deoxyribonucleoprotein and DNA-protein complex is reported. The system utilizes a C8 Ultrasphere macroporous column and an acetonitrile "inverse or negative gradient."
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Affiliation(s)
- L P Kurochkina
- A. N. Belozersky Laboratory of Molecular Biology and Bioorganic Chemistry, Moscow State University, USSR
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38
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39
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Hearn MT, Hodder AN, Aguilar MI. High-performance liquid chromatography of amino acids, peptides and proteins. LXXXVII. Comparison of retention and bandwidth properties of proteins eluted by gradient and isocratic anion-exchange chromatography. J Chromatogr A 1988; 458:27-44. [PMID: 3235638 DOI: 10.1016/s0021-9673(00)90551-x] [Citation(s) in RCA: 17] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/04/2023]
Abstract
The high-performance ion-exchange gradient-elution behaviour of a range of globular proteins has been investigated, using a strong anion exchanger as the stationary phase and sodium chloride as the displacer salt. Deviations were observed between the Zc values obtained from isocratic experiments and from gradient experiments with varied gradient time and varied flow-rate. These results indicate that theoretical treatments which relate gradient and isocratic elution processes do not adequately describe the retention behaviour of protein solutes separated by ion-exchange methods. Furthermore, the experimentally observed bandwidths deviated significantly from values predicted on the basis of plate theory for low-molecular-weight molecules. The significance of these results is discussed in terms of the influence of experimental parameters on the ability of particular electrostatically interactive areas on the surface of protein solutes to control the thermodynamic and kinetic properties of these polyelectrolyte molecules during ion-exchange chromatographic processes.
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Affiliation(s)
- M T Hearn
- Department of Biochemistry, Monash University, Clayton, Victoria, Australia
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40
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Nugent KD, Burton WG, Slattery TK, Johnson BF, Snyder LR. Separation of proteins by reversed-phase high-performance liquid chromatography. II. Optimizing sample pretreatment and mobile phase conditions. J Chromatogr A 1988; 443:381-97. [PMID: 3049650 DOI: 10.1016/s0021-9673(00)94809-x] [Citation(s) in RCA: 68] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/03/2023]
Abstract
The effects of separation variables such as temperature, pH and composition of the mobile phase (including additives such as chaotropes, ion-pairing agents and surfactants), sample size and sample pretreatment for reversed-phase high-performance liquid chromatography (RP-HPLC) of proteins is examined. Experimental optimization of these parameters using the preferred instrumental and column conditions described previously lead to well behaved chromatographic performance for most proteins. This allowed us to achieve the required level of performance for the first dimension (RP-HPLC) separation of most protein samples by the chromatophoresis process.
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41
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Burton WG, Nugent KD, Slattery TK, Summers BR, Snyder LR. Separation of proteins by reversed-phase high-performance liquid chromatography. I. Optimizing the column. J Chromatogr A 1988; 443:363-79. [PMID: 2844841 DOI: 10.1016/s0021-9673(00)94808-8] [Citation(s) in RCA: 88] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/02/2023]
Abstract
In the process of developing a new analytical technology (the chromatophoresis process) which couples reversed-phase high-performance liquid chromatography (HPLC) to sodium dodecyl sulfate polyacrylamide gel electrophoresis in a real-time automated system, it was apparent that improvements in resolving power for the first-dimension (HPLC) separation were necessary. The present paper describes the optimization of the column for our initial work on reversed-phase HPLC separations. Polymeric (polystyrene) packings having particle diameters of 5 micron and pore diameters of 300 A were generally superior in terms of resolution, sample recovery and minimization of "ghosting". Optimum column dimensions were 50 x 1.0 mm I.D. for the flow-rates required in our system (10-100 microliter/min).
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42
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Hearn MT, Aguilar MI, Mant CT, Hodges RS. High-performance liquid chromatography of amino acids, peptides and proteins. LXXXV. Evaluation of the use of hydrophobicity coefficients for the prediction of peptide elution profiles. J Chromatogr A 1988; 438:197-210. [PMID: 3384884 DOI: 10.1016/s0021-9673(00)90250-4] [Citation(s) in RCA: 22] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/05/2023]
Abstract
The gradient elution behaviour of five synthetic decapeptide analogues has been investigated using an octadecylsilica stationary phase and trifluoroacetic acid-water-acetonitrile mobile phases. The influence of gradient time and flow-rate on the relative retentions and bandwidths of these peptides was assessed using quantitative expressions derived from linear solvent strength theory and general plate height theory. Linear relationships between logarithmic median capacity factors, log k, and the mole fraction of organic solvent modifier, phi, were observed over the experimental range of conditions used. The slopes of these plots were different for all peptides, which indicates that divergences will occur in the prediction of peptide retention times due to conformation dependent changes in hydrophobic contact area occupancy at the stationary phase surface. However, the differences in S values (tangent to the curve obtained in a plot of log k versus phi) for these peptides were not substantial enough to seriously affect the prediction of peptide retention times at one gradient slope from those observed at another. In addition, significant differences existed between experimental and theoretical peak capacity data of these peptide analogues of similar molecular weight and overall polarity, particularly at lower flow-rates or longer residence times. These results once again demonstrate that additional diffusional and interactive processes occur during the reversed-phase separation of peptides and proteins which are not yet adequately formalized by current chromatographic theory.
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Affiliation(s)
- M T Hearn
- Department of Biochemistry, Monash University, Clayton, Victoria, Australia
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43
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Hearn MT, Aguilar MI, Nguyen T, Fridman M. High-performance liquid chromatography of amino acids, peptides and proteins. LXXXIV. Application of derivative spectroscopy to the study of column residency effects in the reversed-phase and size-exclusion liquid chromatographic separation of proteins. J Chromatogr A 1988; 435:271-84. [PMID: 3346342 DOI: 10.1016/s0021-9673(01)82187-7] [Citation(s) in RCA: 17] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/05/2023]
Abstract
The influence of column residency times on the reversed-phase gradient elution behaviour of human and bovine growth hormones has been investigated using on-line photodiode array spectroscopic detection. Stationary phase induced effects on protein conformation were monitored by changes in the maxima to minima ratio of the second derivative spectrum of the eluted protein. Significant changes in the second derivative ratio of the unmodified and the fully reduced and alkylated protein were observed following long incubation times, i.e. t(dwell) greater than 15 min, at the stationary phase surface in the presence of 0.1% trifluoroacetic acid before elution with a 0-75% aqueous acetonitrile gradient. The application of multi-wavelength detection in the study of equilibrium unfolding of growth hormones in urea by size-exclusion chromatography was also investigated. On-line photodiode array instrumentation and derivative spectra rationing was employed to monitor tertiary and quaternary structural changes associated with protein denaturation during a chromatographic separation. These studies clearly demonstrate the powerful detection capabilities of such instrumental approaches for the on-line evaluation of both stationary phase surface and/or mobile phase mediated changes in protein conformation.
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Affiliation(s)
- M T Hearn
- Department of Biochemistry, Monash University, Clayton, Victoria, Australia
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44
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Marriott PJ, Lai YH. Capillary column gas chromatographic method for the study of dynamic intramolecular interconversion behaviour. J Chromatogr A 1988. [DOI: 10.1016/0021-9673(88)90004-0] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/27/2022]
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45
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46
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47
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Abstract
Chromatographic retention is determined by a relatively small number of amino acids located in a chromatographic contact region on the surface of a polypeptide. This region is determined by the mode of separation and the amino acid distribution within the polypeptide. The contact area may be as small as a few hundred square angstroms in bioaffinity chromatography. In contrast, the contact region in ion exchange, reversed phase, hydrophobic interaction and the other nonbioaffinity separation modes is much broader, ranging from one side to the whole external surface of a polypeptide. Furthermore, structural changes that alter the chromatographic contact region will alter chromatographic properties. Thus, although immunosorbents can be very useful in purifying proteins of similar primary structure, they will be ineffective in discriminating between small, random variations within a structure. Nonbioaffinity columns complement affinity columns in probing a much larger portion of solute surface and being able to discriminate between protein variants.
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Affiliation(s)
- F E Regnier
- Department of Biochemistry, Purdue University, West Lafayette, IN 47907
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48
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Reitsma BH, Yeung ES. Reversed-phase high-performance liquid chromatography of soybean trypsin inhibitor with optical activity and ultraviolet absorbance detection. J Chromatogr A 1987; 405:295-303. [PMID: 3693469 DOI: 10.1016/s0021-9673(01)81770-2] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/07/2023]
Abstract
The high-performance liquid chromatography of soybean trypsin inhibitor is re-examined by using simultaneous optical activity and ultraviolet absorption detection. Ratio plots of the two detector responses allow easy identification of impurities that are not related to the protein. The specific rotations of each of the separated components can be derived. We find that one denatured form has a distinctly lower specific rotation while another form shows no change in specific rotation. The on-column denaturation rate here was found to be slower than that from previous work. Column pretreatment may have resulted in milder column conditions through the elimination of irreversibly adsorbing sites.
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49
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Hearn MT. General strategies in the separation of proteins by high-performance liquid chromatographic methods. JOURNAL OF CHROMATOGRAPHY 1987; 418:3-26. [PMID: 3305545 DOI: 10.1016/0378-4347(87)80002-6] [Citation(s) in RCA: 18] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/05/2023]
Abstract
General fractionation strategies for the high-resolution purification of proteins are described. The impact of different separation parameters and resolution optimisation approaches with tandem-based systems on retention and recovery behaviour is reviewed. Procedures for the successful linkage of different chromatographic steps into a preferred sequence of operations are discussed in terms of the underlying principles and modus operandi of high-performance liquid chromatographic purification of proteins and related biomacromolecules.
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50
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Hearn MT, Aguilar MI. High-performance liquid chromatography of amino acids, peptides and proteins. LXXIII. Investigations on the relationships between molecular structure, retention and band-broadening properties of polypeptides separated by reversed-phase high-performance liquid chromatography. J Chromatogr A 1987; 397:47-70. [PMID: 3654834 DOI: 10.1016/s0021-9673(01)84989-x] [Citation(s) in RCA: 33] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/06/2023]
Abstract
The gradient retention behaviour in reversed-phase high-performance liquid chromatography of a series of polypeptides related to human beta-endorphin has been investigated using different n-alkylsilica stationary phases and 0.1% trifluoroacetic acid in water-acetonitrile as mobile phase. In particular, the influence of changes in gradient time and flow-rate on retention parameters has been assessed with five different porous octadecylsilica phases with average particle diameters of 4 microns and 6 microns. Decreasing the pore size from 30 nm to 7.3 nm resulted in decreased S and log k'o values for most solutes. The effect of changes in the gradient steepness parameter, b, on the bandwidth behaviour of these polypeptides has also been investigated. Anomalous band-broadening was observed for very steep and very shallow gradients, i.e. b greater than 0.7 or b less than 0.2. The significance of these results is discussed in relation to the presence of hydrophobic domains in the linear sequence, the probability of the formation of highly stabilised secondary structures and the possible involvement of multiple folded forms of a single solute in the chromatographic performance of these polypeptides.
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Affiliation(s)
- M T Hearn
- Department of Biochemistry, Monash University, Clayton, Victoria, Australia
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