Mass spectrometry in de novo sequencing of the skin peptides from Arkhangelsk, Russia Rana temporaria: The variability of secreted AMPs in different populations

Amphibians are one of the oldest classes of vertebrates inhabiting the Earth. Meanwhile, the only weapon their majority possess involves exclusively peptide cocktail secreted by their skin glands in stress conditions. These peptides are considered potential pharmaceuticals of future generations as the mechanism of their interaction with pathogenic microbiota differs greatly from that of the modern antibiotics. High resolution tandem mass spectrometry showed itself as the most powerful tool to uncover the primary structure (sequence) of peptides. In the present study that analytical tool was used to establish skin peptidome of the Rana temporaria frog population from Arkhangelsk, Russia. Thirty-four peptides were sequenced while five of them turned out to be novel. The established peptidome was compared with those of studied earlier populations of Rana temporaria specie (Moscow, central Slovenian, and Italian). Temporins were proposed to be the most variable peptide family responsible for the adaptation of Rana temporaria frog to the conditions of their habitat. The EThcD MS3 method of fragmentation demonstrated its excellent ability to deal with intact disulfide-containing peptides, short peptides capable of cyclizing in conditions of MS/MS experiment, and isomeric Leu/Ile residues. (c) 2022 Elsevier B.V. All rights reserved.

Automated summary

Amphibians, the oldest class of vertebrates, possess a unique weapon in stress conditions - a peptide cocktail secreted by their skin glands. These peptides have a potential as future pharmaceuticals due to their different mechanism of interaction with pathogenic microbiota compared to modern antibiotics. High resolution tandem mass spectrometry was used to establish the skin peptidome of Rana temporaria frog population from Arkhangelsk, Russia. The analysis revealed 34 sequenced peptides, including five novel ones. Temporins were identified as the most variable peptide family responsible for the adaptation of Rana temporaria to their habitat conditions. The EThcD MS3 fragmentation method demonstrated its excellent ability to analyze intact disulfide-containing peptides, cyclizing peptides, and isomeric residues.