CAPILLARY ELECTROPHORESIS COMBINED WITH CF-252 PLASMA DESORPTION AND ELECTROSPRAY MASS-SPECTROMETRY FOR THE STRUCTURAL CHARACTERIZATION OF HYDROPHOBIC POLYPEPTIDES USING ORGANIC-SOLVENTS

Capillary electrophoresis (CE) conditions have been developed for the separation of hydrophobic polypeptides, such as fatty acid-acylated pe ptides, and their subsequent structural identification by Cf-252 plasm a desorption (PDMS) and electrospray mass spectrometry (ESMS). Salt- a nd detergent-free aqueous acetic acid buffers containing up to 20% 2-p ropanol or 25% acetonitrile were employed for CE separations of hydrop hobic peptides with (i) untreated, and (ii) 3-aminopropyltrimethoxysil ane-derivatized fused silica capillaries. For both capillary types, el ectroosmotic flow rates suitable for sample isolation and transfer wer e determined, and CE separations of polypeptide mixtures were compared for aqueous buffers containing 2-propanol or acetonitrile. For the ma ss spectrometric identification of CE-separated peptides, a sheath flo w sample isolation method was developed for subsequent transfer to PDM S. This procedure enabled the efficient isolation of peptide fractions for PDMS analysis, or alternative microanalytical techniques.