Displacement Chromatography of Proteins in Ion Exchange Systems (with Professor Moore)

We have been actively involved in both theoretical and experimental studies on ion exchange protein displacement chromatography. A steric mass-action (SMA) model of nonlinear ion-exchange chromatography has been developed which has made significant strides in understanding some of the complexities of ion-exchange displacement separations. We have discovered that in contrast to the conventional wisdom, low molecular weight displacers can be employed for high resolution protein purifications in ion exchange systems. In addition to representing a paradigm shift in the field of displacement chromatography, these low molecular weight displacers are very important industrially since they have significant operational advantages as compared to large polyelectrolyte displacers.  We have also demonstrated that this technique can be successfully employed for difficult protein purifications from complex biological mixtures (e.g. variants and glycoforms). We are currently carrying out a detailed investigation into the relationship between displacer chemistry and efficacy in various classes of ion exchange materials.

Representative Abstracts:

Shukla, AA; Bae, SS; Moore, JA, et al. “Structural characteristics of low-molecular-mass displacers for cation-exchange chromatography - II. Role of the stationary phase”, J. Chromatogr,  827: (2) 295-310 (1998).
The relative efficacy of a variety of low-molecular-mass displacers was examined on three different stationary phase materials. Several homologous series of displacer molecules were evaluated on these ion-exchange resins using a displacer ranking plot based on the Steric Mass Action (SMA) model. The results demonstrate that while aromaticity and hydrophobicity can play a significant role in the affinity of displacer molecules on polymethacrylate based and hydrophilized polystyrene divinyl benzene based materials, this effect is much less pronounced on an agarose based resin. The work presented in this paper demonstrates that different structural features of low-molecular-mass displacers can dominate their affinity on various stationary phase materials employed and provides rules of thumb for the design of high affinity, low-molecular-mass displacers for a variety of commercial cation-exchange materials.