Sequencing of cyclic peptides by NMR and MS techniques demonstrated on stylissamides A–F

Abstract

The Caribbean sponge Stylissa caribica is the source of a series of six proline-rich cyclic heptapeptides, the stylissamides A–F (1–6). Here, we review the elucidation of the structures of 1–6 by a combination of NMR and mass spectrometry (MS/MS and MSn experiments). A detailed description of the NMR analysis (including semi-selective 1H,13C-HMBC and NOESY experiments) for sequencing the peptides is provided for stylissamides A (1) and E (5).