CHIRAL SEPARATION OF BETA-BLOCKERS BY HIGH-PERFORMANCE CAPILLARY ELECTROPHORESIS BASED ON NON-IMMOBILIZED CELLULASE AS ENANTIOSELECTIVE PROTEIN

Optical isomers of some basic parmaceutical drugs (beta-blockers) were separated by means of high-performance capillary electrophoresis in a carrier-free solution, using the chiral recognition properties of a c ellulase (cellobiohydrolase I). High resolution of the isomers and pea ks with satisfactory symmetry were obtained only when the enzyme was d issolved at a high concentration (40 mg/ml; total 10 mug) in a buffer of high ionic strength (0.4 M sodium phosphate) supplemented with 2-pr opanol. Surprisingly, the isomer selectivity was lost when the electro phoresis was carried out in the buffers used for chromatographic separ ation of the isomers on a bed derivatized with cellulase. At pH 5.1 (t he experimental pH), the enantiomers are positively charged and the en zyme is negatively charged. With the cathode at the detection end of t he capillary the enzyme accordingly migrated away from the detection p oint and the enantiomers toward it. Disturbances in the UV detection o f the enantiomers otherwise caused by the presence of the enzyme were thus avoided. As the runs are performed in the absence of a supporting medium the analyses can be automated easily, which also facilitates t he screening of different proteins for their chiral recognition proper ties and studies to establish the optimum experimental conditions.