Sequence analysis of lantibiotics: chemical derivatization procedures allow a fast access to complete Edman degradation.

Lantibiotics are antibiotic peptides produced via ribosomal synthesis of precursor proteins by gram-positive bacteria. They contain various unusual post-translational modifications, which include the formation of sulfide rings by lanthionine or beta-methyllanthionine, and 2,3-didehydroamino acids. The N-terminus may be blocked by a 2-oxobutyryl group and the C-terminus may be inaccessible in some of the lantibiotics. Due to these modifications the analysis of such peptides is very tedious. Chemical modifications using an ethanethiol-containing reaction mixture and/or trifluoroperacetic acid treatment were used to solve these analytical problems. Investigating the tetracyclic 22-peptide gallidermin and the N-terminally blocked tricyclic 34-peptide Pep5 as examples, a novel access to the primary structure of lantibiotics is demonstrated.