Living organisms discriminate between the enantiomers of chiral compounds, e.g., drugs, at virtually all levels of interaction, and respond differently to them. While one enantiomer may exhibit a desired activity, the other may cause severe pharmacologic and toxicologic side effects, or act as an antagonist. However, more than half of the 500 top selling drugs and about two-thirds of the drugs presently in development are chiral. Since 1988 the FDA demands not only the quantitative determination of the stereo isomeric composition of chiral drugs, but also stereochemically specific identity tests, as well as pharmacologic and pharmacokinetic characterization of the individual enantiomers. The development of refined analytical techniques and selectors for the precise determination of bioactive chiral molecules and their purification is therefore of great interest. Direct resolution of enantiomers in chromatographic or electrophoretic systems is based on their differential interactions with a chiral selector. Although approximately 200 chiral selectors are currently commercially available, these selectors are generally not tailor-made for a specific separation problem, and the identification of a suitable selector is still a tedious trial-and-error exercise. It has long been known that antibodies can differentiate between the enantiomers of chiral compounds. Since antibodies can furthermore be raised against virtually any compound of interest, we are intrigued by the idea of exploiting the stereoselectivity and specificity of antibodies for the production of tailor-made chiral stationary phases. We propose to develop and study immunoaffinity systems that combine selectivity with ease of use, short analysis times, and long-term stability, and are therefore suitable for routine enantiomer separation. Stereoselective antibodies, or fragments thereof, will be immobilized on conventional and high flow through type solid support materials and employed in pressure- and electrodriven separation techniques such as HPLC, micro-LC, CE, CEC, OTEC, and OTLC. The development of methods that allow enantiomer separation under mild, isocratic conditions favorable for protein stability and activity is of special interest. Chromatographic parameters will be optimized in order to adjust separation conditions to the strength of interaction between antibody and analyte.
