HIGH-PERFORMANCE LIQUID-CHROMATOGRAPHIC SEPARATION OF CIS-TRANS ISOMERS OF PROLINE-CONTAINING PEPTIDES .2. FRACTIONATION IN DIFFERENT CYCLODEXTRIN SYSTEMS

beta-Cyclodextrin-bonded silica is demonstrated to be a suitable stati onary phase for high-performance liquid chromatography of conformation al isomers of proline-containing peptides. In contrast to reversed-pha se chromatography, the principle of inclusion complexation shows signi ficant selectivities in conformer resolution based on a variety of int eractions. New results of inclusion HPLC of biologically active oligop eptides related to beta-casomorphin on stationary phases containing bo nded cyclodextrins of different internal diameters indicate a steric d iscrimination process during the conformer separation. beta-Cyclodextr in used as a mobile phase additive in reversed-phase systems is shown to offer the opportunity to investigate conformational changes using c ommercially available reversed-phase columns.