Recent advances in peptide and peptidomimetic stereoisomer separations by capillary electromigration techniques

Abstract

As the stereochemistry of peptides determines their physicochemical properties and biological activities, analytical methods able to discriminate between peptide stereoisomers are important especially with regard to pharmaceutical peptides and peptidomimetics. The present review summarizes recent developments in peptide and peptidomimetic stereoisomer separations by capillary electromigration techniques. The majority of separations were performed by CE while only few reports have been published on the subject of electrochromatography. In addition to systematic studies on the applicability of certain buffer additives and the evaluation of specific experimental conditions, there have been attempts to understand the mechanistic aspects of peptide stereoisomer separations as well as to analyze the structure of peptide-CD complexes.

Influence of buffer substances and urea on the β‐cyclodextrin‐mediated chiral separation of dipeptides in CE

“…CDs are by far the most utilized chiral selectors in CE [3]. The great application potential of CE to enantioseparations of small peptides has been highlighted [4][5][6][7].…”

Separation of multiphosphorylated peptide isomers by CZE

“…Moreover, most of these RP-techniques are not favorably coupled to MS. As phosphopeptide isomers are isobaric they have to be separated before being analyzed by MS techniques. As most other chromatographic techniques are either unable to separate phosphopeptide isomers or are not compatible with MS, CE appears to be a promising alternative [6][7][8][9][10][11]. Moreover, the low phosphopeptide quantities typically obtained from a protein digest fit well with the high mass sensitivity of CE techniques and ideally the electrolyte is compatible to ESI-and MALDI-MS. Gamble and colleagues introduced a formic acid system to separate a doubly phosphorylated sequence from the corresponding two monophosphorylated and unphosphorylated peptides [8].…”

Recent developments in CE and CEC of peptides

“…Hence, the separation of enantiomers is of paramount importance. Due to the high efficiency, resolution power, speed, and miniaturization, CE and CEC techniques have become very powerful and frequently used methods for chiral analysis and stereoisomer separation [229] including chiral and stereoselective separations of peptides as demonstrated in the reviews [15,16]. With respect to the comprehensive survey of peptide stereoseparations in these reviews, only few representative examples of peptide stereoseparations are briefly mentioned in this section.…”

“…Applications of these methods to analysis and characterization of peptides have been further broadened, and CE and Abbreviations: ìTAS, micrototal analytical systems; CABCE, carrier ampholyte-based CE; CAE, capillary affinity electrophoresis; CEKC, capillary EKC; CITP, capillary ITP; CMEKC, capillary MEKC; CSF, cerebrospinal fluid; EMMA, electrophoresis-mediated microanalysis; FS, fused-silica; GnRHs, gonadotropin-releasing hormones; GSH, glutathione; GSSG, glutathione-disulfide; LLE, liquid-liquid extraction; MBB, monobromo-bimane; MICAE, multiple-injection CAE; NBD-F, 4-fluoro-7-nitro-2,1,3-benzoxadiazole; NDA, naphthalene-2,3-dicarboxyaldehyde; OT-CEC, open tubular CEC; SPME, solid-phase microextraction; 2008,29, CEC techniques are nowadays accepted as a recognized counterpart and/or complement to the earlier well-established techniques for peptide analysis and preparation -different modes of HPLC. In addition to the last one of the above reviews [11], the advances of CE and CEC of peptides in recent years are described also in some other reviews dealing with CE and CEC of biomolecules in general [12][13][14] and with some particular topics of CE and CEC of peptides [15][16][17], and in the recent special issue of Electrophoresis devoted to CE and CEC of amino acids, peptides and proteins [18]. …”