The crude skin secretion of the pepper frog leptodactylus labyrinthicus is rich in metallo and serine peptidases

Libério, Michelle S., Bastos, Izabela M.D., Pires Júnior, Osmindo R., Fontes, Wagner, Santana, Jaime M., & Castro, Mariana S. (2014) The crude skin secretion of the pepper frog leptodactylus labyrinthicus is rich in metallo and serine peptidases. PLoS ONE, 9(6), e96893-1.

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Abstract

Peptidases are ubiquitous enzymes involved in diverse biological processes. Fragments from bioactive peptides have been found in skin secretions from frogs, and their presence suggests processing by peptidases. Thus, the aim of this work was to characterize the peptidase activity present in the skin secretion of Leptodactylus labyrinthicus. Zymography revealed the presence of three bands of gelatinase activity of approximately 60 kDa, 66 kDa, and 80 kDa, which the first two were calcium-dependent. These three bands were inhibited either by ethylenediaminetetraacetic acid (EDTA) and phenathroline; thus, they were characterized as metallopeptidases. Furthermore, the proteolytic enzymes identified were active only at pH 6.0–10.0, and their activity increased in the presence of CHAPS or NaCl. Experiments with fluorogenic substrates incubated with skin secretions identified aminopeptidase activity, with cleavage after leucine, proline, and alanine residues. This activity was directly proportional to the protein concentration, and it was inhibited in the presence of metallo and serine peptidase inhibitors. Besides, the optimal pH for substrate cleavage was determined to be 7.0–8.0. The results of the in gel activity assay showed that all substrates were hydrolyzed by a 45 kDa peptidase. Gly-Pro-AMC was also cleaved by a peptidase greater than 97 kDa. The data suggest the presence of dipeptidyl peptidases (DPPs) and metallopeptidases; however, further research is necessary. In conclusion, our work will help to elucidate the implication of these enzymatic activities in the processing of the bioactive peptides present in frog venom, expanding the knowledge of amphibian biology.

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ID Code: 74641
Item Type: Journal Article
Refereed: Yes
Additional Information: This study was supported by the Brazilian National Council for Scientific and Technological Development (CNPq, grant numbers 563972/2010-6 and
302925/2012-0), the Brazilian Federal Agency for the Support and Evaluation of Graduate Education (CAPES), the Funding Authority for Studies and Projects
(FINEP), the Foundation for Research Support of the Federal District (FAPDF, grant numbers 193.000.414/2008 and 193.000.461/2011) and the University of Brasilia
Foundation (FUB/UnB). The funders had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscript.
DOI: 10.1371/journal.pone.0096893
ISSN: 1932-6203
Subjects: Australian and New Zealand Standard Research Classification > BIOLOGICAL SCIENCES (060000) > BIOCHEMISTRY AND CELL BIOLOGY (060100) > Enzymes (060107)
Divisions: Current > QUT Faculties and Divisions > Faculty of Health
Copyright Owner: Copyright 2014 Libe´ rio et al.
Copyright Statement: This is an open-access article distributed under the terms of the Creative Commons Attribution License, which permits
unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited.
Deposited On: 04 Aug 2014 01:56
Last Modified: 04 Aug 2014 21:23

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