Capillary electrochromatographic separation of peptides using a macrocyclic polyamine for molecular recognition

Area of Science:

• Analytical Chemistry
• Separation Science
• Biochemistry

Background:

• Oligopeptide separation is crucial for biochemical analysis.
• Developing efficient and robust separation methods is essential.

Purpose of the Study:

• To utilize a macrocyclic polyamine, 1,5,9,13,17,21,25,29-octaazacyclodotriacontane ([32]ane-N(8)), as a molecular receptor for capillary electrophoresis (CEC) separation of oligopeptides.
• To investigate parameters influencing separation performance.
• To assess the long-term stability of the developed CEC column.

Main Methods:

• Capillary electrophoresis (CEC) using a bonded macrocyclic polyamine stationary phase.
• Optimization of mobile phase composition (phosphate and acetate buffers with pH gradients).
• Analysis of complex peptide mixtures including angiotensins, casomorphins, oxytocin, vasopressin, FMRF amide, and enkephalins.

Main Results:

• Baseline separation of a diverse mixture of eight oligopeptides was achieved using a phosphate buffer (30 mM, pH 7).
• High column efficiency was demonstrated with average theoretical plate numbers of 69,000 plates/m and low relative standard deviations (<1%).
• Complete separation of [Met(5)]-enkephalin and [Leu(5)]-enkephalin with identical pI values was accomplished using an acetate buffer pH gradient.
• The separation mechanism involves a combination of electrophoretic migration and chromatographic retention via anion coordination and exchange.
• The capillary electrophoresis column exhibited excellent long-term stability, with electroosmotic flow (EOF) deviation within 6.0% after over 600 injections.

Conclusions:

• The macrocyclic polyamine stationary phase is effective for CEC separation of oligopeptides.
• The method provides high resolution, efficiency, and robustness for complex peptide analysis.
• The developed CEC system demonstrates significant potential for peptide characterization and quality control.