FT‐MS in the de novo top‐down sequencing of natural nontryptic peptides

Abstract

The present review covers available results on the application of FT-MS for the de novo sequencing of natural peptides of various animals: cones, bees, snakes, amphibians, scorpions, and so forth. As these peptides are usually bioactive, the animals efficiently use them as a weapon against microorganisms or higher animals including predators. These peptides represent definite interest as drugs of future generations since the mechanism of their activity is completely different in comparison with that of the modern antibiotics. Utilization of those peptides as antibiotics can eliminate the problem of the bacterial resistance development. Sequence elucidation of these bioactive peptides becomes even more challenging when the species genome is not available and little is known about the protein origin and other properties of those peptides in the study. De novo sequencing may be the only option to obtain sequence information. The benefits of FT-MS for the top-down peptide sequencing, the general approaches of the de novxxo sequencing, the difficult cases involving sequence coverage, isobaric and isomeric amino acids, cyclization of short peptides, the presence of posttranslational modifications will be discussed in the review.

EThcD Benefits for the Sequencing Inside Intramolecular Disulfide Cycles of Amphibian Intact Peptides

“…Moreover, quite often acetamidation does not enable reaching the analysis goal as, for example, the sequence inside the cleaved intramolecular disulfide cycle remains unavailable due to some structural peculiarities. 4 An alternative version of the S−S bond cleavage involves oxidation with peracids. The reaction proceeds in one stage, while using performic acid it is not necessary to carry out purification, as the forming formic acid easily evaporates.…”

“…The advantages and shortcomings of reduction/ alkylation vs oxidation to analyze intramolecular disulfide bonds in frog peptides have been discussed. 4 It was concluded that to reach the goal of obtaining the full sequence it is better to use both procedures and analyze the results in parallel. 20,26−28 Some natural peptides from snake and spider venoms, as well as cone toxins, often have more than one S−S bond.…”

“…Besides this drawback, two-stage derivatization is time-consuming, while minor constituents of the analyzed peptide mixture may be lost. Moreover, quite often acetamidation does not enable reaching the analysis goal as, for example, the sequence inside the cleaved intramolecular disulfide cycle remains unavailable due to some structural peculiarities. , …”

Mass Spectrometry Differentiation between Rana arvalis Populations Based on Their Skin Peptidome Composition

“…Skin secretion released by the dorsal glands of amphibians in response to the external threat, irritation, or attack represents the main and often the only defensive weapon of amphibians, including Ranid frogs. Our scientific interests deal with the de novo sequencing of the amphibian skin secretion peptides by means of mass spectrometry. − The obtained results are summarized in the recent reviews. , Skin peptidomes of the European Ranid frogs, including Rana arvalis species, may contain the following features: (i) peptides with C-terminal disulfide 6–9 member cycles, called “rana box” (brevinins 1 and 2; esculentins 1 and 2; ranatuerins 1 and 2, and some other peptides’ families); (ii) amidation at the C-terminal temporins; (iii) melittin-related peptides (MRPs); (iv) bradykinin-related peptides (BRPs); (v) bombesins, and others. − Their activity usually leads to the death of pathogenic cells. Thus, disulfide-containing peptides, temporins, and MRPs are treated as cytolytics.…”

“…1−9 The obtained results are summarized in the recent reviews. 10,11 Skin peptidomes of the European Ranid frogs, including Rana arvalis species, may contain the following features: (i) peptides with C-terminal disulfide 6−9 member cycles, called "rana box" (brevinins 1 and 2; esculentins 1 and 2; ranatuerins 1 and 2, and some other peptides' families); (ii) amidation at the C-terminal temporins; (iii) melittin-related peptides (MRPs); (iv) bradykinin-related peptides (BRPs); (v) bombesins, and others. 1−11 Their activity usually leads to the death of pathogenic cells.…”