Advances in Electrokinetic Chromatography: Prospects for Prediction of Two-Dimensional Peptide Maps and High Throughput Drug Screening

Yang Shen, Mehdi Jallali-Heravi, Jennifer Carrozzino, and Morteza Khaledi Department of Chemistry; North Carolina State University; Raleigh, NC, 27695-8204

e-mail: Morteza_Khaledi@ncsu.edu

In this presentation, two unique aspects of Electrokinetic Chromatography (EKC) will be discussed. The focus of the first part is the use of Micellar Electrokinetic Chromatography (MEKC) for peptides separations and mapping. The significant features of MEKC are the availability of a wide range of pseudo-stationary phases that provide unique selectivities for peptides and the feasibility of manipulating the composition of the pseudo-phase since it is a completely solution based technique. In addition, phase ratio in MEKC can be accurately determined as it is related to the surfactant intrinsic properties of surfactant and concentration. Retention factor in MEKC is directly related to micelle – water partition coefficients, K, and the phase ratio. This provides a unique opportunity for a priori prediction of retention behavior in MEKC for solutes with known micelle – water partition coefficient values. Chromatograms of mixtures could then be readily calculated after a single measurement of the elution window boundaries under a given MEKC capillary and buffer conditions.

The use of Quantitative Structure-Partitioning Relationships (QSPR) for calculation of micelle-water partition coefficient of peptides from structural descriptors will be presented. Special attention will be given to partitioning behavior of peptides in various micellar pseudo-phases. The ability to predict migration patterns of peptides is a great advantage in optimization of separations of complex mixtures of peptides. These models have been used to predict peptides maps of digests of horse heart Cytochrome C. The prospects of predicting two-dimensional peptides separation of MEKC – CZE will be discussed.

In the second part the use of Liposome Electrokinetic Chromatography (LEKC) for high throughput drug screening for prediction of oral bioavailability and membrane permeability will be presented. The migration behavior in LEKC is used to determine liposome – water partition coefficient that could be used as a lipophilicity scale for modeling drug interactions with cell membranes in ADME studies in drug discovery and in Quantitative Structure Activity Relationships (QSAR).