Protein denaturation in nonlinear isocratic and gradient elution chromatography

Abstract

Protein denaturation, common in hydrophobic adsorption systems, causes misinterpretation of adsorption mechanisms, interferes with analysis in analytical chro matograph-v, and

Modeling gradient elution of proteins in ion‐exchange chromatography

“…Further, since both types of models require similar (though not identical) parameter estimation experiments, their use in a complementary fashion is quite convenient. Of course, solution of the full problem including dispersion, nonlinear adsorption, and multicomponent competitive binding is possible using numerical methods (Yamamoto et al, 1983a,b;Antia and Horvhth, 1989;Snyder et al, 1991;Gu et al, 1992;Bellot and Condoret, 1993;Whitley et al, 1994). Greek letters A = change in a variable across a discontinuity E = total porosity of column 0 = function that gives Q2 along a particular characteristic when supplied with x and r * A = column capacity for a monovalent salt counterion, mM E = function that gives x along a particular characteristic when T* = function that gives r* along a particular iharacteristic when supplied with T* and Q2…”

“…The problem of adsorption described by the Langmuir and other constant separation factor isotherms has been studied quite extensively, and a number of analytical solutions have been presented (Helfferich and Klein, 1970;Rhee et al, 1986). However, for most other isotherms, investigators have resorted to numerical methods for solution of the mass transport and adsorption equations describing chromatography (Yamamoto et al, 1983a,b;Antia and HorvAth, 1989;Czok and Guichon, 1990a,b;Snyder et al, 1991;Ma and Guichon, 1991;Gu et al, 1992;Bellot and Condoret, 1993;Whitley et al, 1994). However, the use of a nonconstant separation factor isotherm does not, in itself, prevent an analytical solution of a given problem, even if that isotherm is nonlinear.…”

Tracking lysozyme unfolding during salt-induced precipitation with hydrogen exchange and mass spectrometry

“…A protein's solubility depends strongly on its conformation (Lumry and Eyring, 1954;Stigter and Dill, 1993), thus limiting concentrations that can be achieved and maintained during downstream processing steps where mildly denaturing conditions are used. Conformational changes can also occur upon adsorption to chromatography media (McNay and Fernandez, 1999;Sane et al, 1999), which generally results in undesirable changes in retention behavior (Benedek et al, 1984;Whitley et al, 1994), but can also be exploited to separate closely related protein variants (Oroszlan et al, 1992). Furthermore, although pharmaceutical formulations generally include solutes that increase protein stability, maintaining biological activity during the shelf-life and delivery of the product is not easily guaranteed (Cleland et al, 1993;Constantino et al, 1995;Tzannis et al, 1996).…”

Design of a Fission 99Mo Recovery Process and Implications toward Mo Adsorption Mechanism on Titania and Alumina Sorbents

“…The VERSE model and related simulations were developed by Wang and associates in 1991 . The general VERSE model takes into account detailed intrinsic (or scale-independent) parameters, which include the system parameters (particle porosity and bed void fraction), adsorption isotherms, Brownian diffusivities, intraparticle pore diffusivities, axial dispersion, film mass transfer, intraparticle pore and surface diffusion, slow adsorption and desorption, and possible chemical reactions in the mobile phase or in the solid phase during the separations. − Although the general VERSE model can take into account parallel intraparticle pore and surface diffusion, previous studies have shown that at a relatively low concentration, the effects of surface diffusion on frontal or elution chromatography cannot be distinguished from those of pore diffusion. As a result, a pore-diffusion model can be used to predict closely the frontal curves. , Since the Mo feed concentration in the system of interest is relatively low (∼10 –3 mM), the pore-diffusion model was tested for process simulation and design.…”