Ocurrence of a Somatostatin-like Peptide in the

skin secretion of Hylapunctata (ANURA)

Prates, M.V.(1,2), Sforça, M.L.(3), Figueredo, R.C.R.(3), Gordo, M.(4), Sebben, A.(5), Spisni, A.(3), Bloch Jr, C.(1)

(1)Laboratório de Espectrometria de Massa, Embrapa, Recursos Genéticos e Biotecnologia, Brasília, DF, (2)Departamento de Biologia Celular, Instituto de Ciências Biológicas, Universidade de Brasília, Brasília, DF, (3)Centro de Biologia Molecular Estrutural, Laboratório Nacional de Luz Síncrotron, Campinas, SP, (4)Departamento de Biologia, Universidade do Amazonas, Manaus, AM, (5)Laboratório de Toxinologia, Departamento de Biologia Animal, Instituto de Ciências Biológicas, Universidade de Brasília, Brasília, DF.

Introduction: Anurans produce powerful host defense compounds in their skin secretion, including bioactive peptides displaying antibiotic, antiviral, antifungal, anticancer and hormonal activities (Weneger, K. L. et al. 2001, RCM 1726-1734). Recently, we have isolated a somatostatin-like neuropeptide from the skin secretion of the Brazilian hylid Hyla punctata.

Objectives: The main goal of this work was the purification, synthesis and 3D structure determination of the somatostin-like peptide isolated from  H. punctata.

Methods: Purification of the natural somatostatin-like peptide by RP- HPLC, purity and mass analysis by MALDI-TOF/MS, N-terminal sequencing by automatic Edman's degradation, F-moc automatic solid-phase synthesis, Circular dichroism (CD) and 2D ¹H NMR studies in H₂O.

Results:The 15-residue neuropeptide Hp-somatostatin was sinthesized and its molecular weight was determined to be 1832.80 Da. CD and 2D ¹H NMR studies, carried out in water indicate the presence of a preferential 3D fold.

Conclusions: Somatostatin is a 14-residue peptide hormone found in superior vertebrates, synthesized  in the hypothalamus and pancreatic islets. It plays an important role in the regulation of various hormones, such as growth hormone, insulin, glucagon and gastrin (Tran. TA.,et al. 1998, J. Med. Chem. 2679-2685).  The actual function of Hp-somatostatin found in the skin secretion of H. punctata is unclear. A possible explanation might be that it is part of a defence mechanism, however, this needs to be further investigated.

Support: UnB, EMBRAPA, CNPq, FAPESP.

CORRESPONDENCE TO:

Maura Vianna Prates, HCGN 707 BL. F CS. 19, Brasília, DF, CEP: 70740-736, Brasil, Email: maura@cenargen.embrapa.br