Purification and Characterization of a New Peptide Included in the Labyrinthin Family from the Skin Secretion of Leptodactyluslabyrinthicus

Zanotta, L.C.(1,2), Fontes, W.(2), Sousa, M.V.(2), Schwartz, C.A.(1), Schwartz, E.F.(1), Sebben, A.(1), Castro, M.S.(1,2)

(1)Laboratório de Toxinologia, Departamento de Ciências Fisiológicas, IB, (2)CBSP – Centro Brasileiro de Serviços e Pesquisas em Proteínas, Departamento de Biologia Celular, IB, Universidade de Brasília, Brasília, DF, Brasil.

It is already known that the skin secretion of anurans presents a large number of bioactive compounds that, among other activities, are involved in defending the organism against predators and microbial infections. We have previously described a new family of putative antimicrobial peptides from skin secretion of Leptodactylus labyrinthicus, called Labyrinthins. The peptides included in this family present a large number of hydrophobic residues, no cystein residues and an amidated C-terminus. Moreover, the peptides of this family have low sequence similarity to other antimicrobial peptide families. In the present report we describe the purification and characterization of a new peptide isolated from the cutaneous secretion of Leptodactylus labyrinthicus. The animals were collected in Distrito Federal region and the skin secretion was obtained by mild electrical stimulation and immediately lyophilized. Dried secretion was dissolved in 0.1% (v/v) TFA/water and applied onto a Pharmacia C₈ column and elution was performed using a linear acetonitrile gradient. The fraction of interest was rechromatographed using a Vydac C₁₈ column. Its primary structure was obtained by Edman degradation (ABI 477A sequencer) and its molecular mass was determined using a triple-quadrupole mass spectrometer (PE-Sciex API 300). The purification procedure resulted in the isolation of a highly homogenous fraction with molecular mass of 2192.60 kDa. The N-terminal sequence obtained displayed high similarity to Labyrinthins1 and 2, recently isolated from this skin secretion by our group. Due to the observed homology, we discuss that Labyrinthins probably have antimicrobial properties.

CORRESPONDENCE TO:

LanuseCaixeta Zanotta, AOS 04 Bloco A Apartamento 420, Brasília, DF, CEP: 70660-041, Brasil, Email: lanazanotta@yahoo.com.br