Chromatographic and Mass-Spectrometric Identification of Linear and Cyclic Peptides Based on Glycine

Abstract

The retention of glycine-based peptides on a Hypercarb carbon adsorbent is studied by reversed-phase HPLC. In the reaction mixture obtained in the synthesis of polyglycines, ions corresponding to both linear and cyclic peptides are detected by electrospray ionization mass spectrometry. Characteristics of the retention of the components are determined on varying the composition of the mobile phase in the isocratic mode. It is shown that some of the detected ions are fragmented ions of linear polyglycines rather than protonated individual cyclic peptides, which complicated identification. The presence of five linear polyglycines as well as cyclodiglycine in the test mixture is confirmed.