Characterization of two novel antimicrobial peptides from the cuticular extracts of the ant Trichomyrmex criniceps (Mayr), (Hymenoptera: Formicidae).

Antimicrobial peptides (AMPs) from cuticular extracts of worker ants of Trichomyrmex criniceps (Mayr, Hymenoptera: Formicidae) were isolated and evaluated for their antimicrobial activity. Eight peptides ranging in mass from 804.42 to 1541.

Combined electron transfer dissociation-collision-induced dissociation fragmentation in the mass spectrometric distinction of leucine, isoleucine, and hydroxyproline residues in Peptide natural products.

Distinctions between isobaric residues have been a major challenge in mass spectrometric peptide sequencing. Here, we propose a methodology for distinction among isobaric leucine, isoleucine, and hydroxyproline, a commonly found post-translationally modified amino acid with a nominal mass of 113 Da, through a combined electron transfer dissociation-collision-induced dissociation approach. While the absence of c and z(•) ions, corresponding to the Yyy-Xxx (Xxx = Leu, Ile, or Hyp) segment, is indicative of the presence of hydroxyproline, loss of isopropyl (Δm = 43 Da) or ethyl radicals (Δm = 29 Da), through collisional activation of z radical ions, are characteristic of leucine or isoleucine, respectively.