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Open Access Publications from the University of California

Mass spectrometric and bioinformatics approaches to characterizing of cyclic non-ribosomal peptides and ribosomally encoded peptide antibiotic

  • Author(s): Liu, Wei-Ting
  • et al.

Natural products are a crucial component in drug discovery because of their considerable pharmaceutical properties. Cyclic non-ribosomally peptides are one category of natural products featured by containing non-standard amino acids and lactam or lactone structures, thus increasing the complexity of the resulting tandem mass spectrometry data. Cyclosporin, microcystins and nodularins all are well-known examples and have notable pharmacologically importance. In this current work, by collaborating with Dr. Pevzner bioinformatics group, a program was developed for the annotation and characterization of tandem mass spectra obtained from cyclic peptides. This program, MS- CPA is available as a web tool ( cpa_v1/ The second half of this thesis will be focused on a ribosomally encoded peptide antibiotic trifolitoxin produced by a rhizobium strain. This peptide undergoes multiple unknown post-translational modifications results in a loss of 24 Da masses. Mass spectrometry based strategies as well as in vivo reconstitution experiments were used to partially characterize trifolitoxin structure.

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