Influence of the amino acid sequence and nature of the cyclodextrin on theseparation of small peptide enantiomers by capillary electrophoresis usingalpha-, beta-, and gamma-cyclodextrin and the corresponding hydroxypropyl derivatives

The separation of the LL and DD enantiomers of dipeptides and tripeptides u sing alpha-, beta-, and gamma -cyclodextrins as well as the corresponding h ydroxypropyl derivatives was studied with respect to the amino acid sequenc e of the peptides and the nature of the cyclodextrins Standardized conditio ns regarding buffer pH and molarity, cyclodextrin concentration, and separa tion voltage were applied. a-Cyclodextrin, hydroxypropyl-alpha -cyclodextri n, P-cyclodextrin, and hydroxypropyl-p-cyclodextrin were the more universal cyclodextrins for enantioseparations of the investigated set of peptides c ompared to gamma -cyclodextrin and hydroxypropyl-gamma -cyclodextrin. The e nantiomer migration order depended both on the cyclodextrin and on the amin o acid sequence of the peptide. Reversal of the enantiomer migration order upon increasing the buffer pH from 2.5 to 3.5 was observed in some cases us ing beta -cyclodextrin.