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Skin secretions of amphibian are an interesting source of biologically active peptides. The present study provides the profile of the skin secretions of the brown frog Rana temporaria from Zvenigorod population (Russia). Sequencing of the skin secretion components has been carried out on an ion cyclotron resonance instrument with electrospray ionization and two methods of fragmentation activation, collisional activation and electron capture. For sequencing of the peptides containing intermolecular C-terminal disulfide cycle two methods of disulfide bond opening have been used: reduction with subsequent alkylation of the free thiol groups and oxidation with performic acid with the formation of sulfo-acid groups. The peptide profile of Rana temporaria studied by a complex mass spectral method has been compared with the data for the frogs of other European populations of this species. For the first time we have revealed ornithokinin--antagonist of the ornithokinin receptor--in skin secretions of amphibians. Keywords: Rana temporaria, Fourier transformation ion cyclotron resonance, mass spectral sequencing, disulfide-containing peptides, ornithokinin, temporins. DOI: 10.1134/S1061934811140152, INTRODUCTION Recently the area of our interest has moved to the mass spectral investigation of skin peptides of amphibian, in particular, of ranid frogs, true frogs Rana. Due to wide [...]

Amphibian skin secretion represents a cerain scientific interest as a source of biologically active natural peptides. In the present research skin peptidome of wide-spread European frog Rana lessonae (Camerano, 1882) was studied for the first time ever. Peptide sequencing was accomplished with Fourier transform ion cyclotron resonance mass spectrometer in collision-induced and electron capture dissociation modes. A portion of amphibian peptides contains intramolecular C-terminal disulfide cycle which obstructs mass spectrometric sequencing. Two methods were utilized to overcome this difficulty: reduction with dithiotreithol followed by thiol group alkylation and oxidation into sulfonic acid groups with performic acid. Integrated approach employed in the present study allowed the identification of 49 peptides (of 6 to 37 amino acid residues), including 19 novel species. Keywords: Rana lessonae, Fourier-transform ion cyclotrone resonance mass spectrometry, peptide sequencing, disulfide-containing peptides, lessonakinines. DOI: 10.1134/S1061934811130120, INTRODUCTION Skin of amphibians represents a rich source of natural peptides possessing wide spectrum of biological (gram positive and gram negative bacteria, fungi, viruses) activity [1-4]. Some of these antimicrobial [...]

Mass spectrometric de novo sequencing of skin secretion peptides from genus Rana is complicated because of C-terminal disulfide cycles present in their structure. Brevinin-1E and brevinin-2Ec from the skin secretion of the Marsh Frog R. ridibunda were used for a comparative study of six N-phenylmaleimide derivatives as new alkylating agents for cysteine thiol moieties. The paper describes the synthesis and confirmation of the structures of the obtained compounds. A procedure was developed for modifying thiol groups with the proposed reagents. Alkylation efficiency and the effect on the peak intensity in matrix-assisted laser desorption/ionization (MALDI) spectra were investigated. The best results were obtained for 2,4- and 2,5-dimethylphenylmaleimides. Additionally tested iodoacetic acid was shown to be a powerful modifier of thiol groups, while its excess notably increases the intensities of the peaks of protonated molecules in the MALDI mass spectra of both peptides. Keywords: disulfide-containing peptides, alkylation, cysteine, N-phenylmaleimide, MALDI-TOF, iodoacetic acid DOI: 10.1134/S1061934810130034, INTRODUCTION Peptides characterized by a wide spectrum of biological activity are the main components of skin secretions from genus Rana [1-3]. Some of them contain a C-terminal disulfide cycle ('Rana [...]

A number of publications on urgent matters in the development of systems engaged in operation, maintenance and storage (OMS) of weapons and military equipment (WME), including those appearing in Military [...]

The core of the RF Defense Ministry's military-technical policy in the operation and maintenance of arms and military equipment (AME) is ensuring the combat readiness (serviceability) of AME as the [...]