THESIS: E. J. L. Rego submitted this thesis for the degree of Master of Science in Genetics publicly examined at the Institute of Biology, Campinas State University - UNICAMP - Campinas, São Paulo, Brazil in 1995.
Advisor: Professor Benedito Oliveira Filho
ABSTRACT. The venom of the spider Phoneutria nigriventer produces a variety of biological actions including priapism which is characterized by a painful and prolonged penile erection. For the effective penile erection, relaxation of the corpus cavernosum smooth muscle is necessary which is regulated by both the nervous system and nitric oxide. In the rabbit corpus cavernosum, Phoneutria nigriventer venom activates the tissue kallikrein system which produces kinin and consequently nitric oxide release, leading to relaxation of this tissue. A polypeptide from Phoneutria nigriventer responsible for the relaxation of the rabbit corpus cavernosum was purified by high performance liquid chromatography (HPLC). This polypeptide called PNV4 was biochemically characterized by polyacrylamide gel electrophoresis (SDS- PAGE), amino acid composition and N-terminal amino acid sequence using automated Edman degradation. This polypeptide has a molecular mass of 16.9 kDa, 144 amino acid residues and the following N-terminal sequence: A E L T S C F P V G H E C D G D A S N C N C C G D D V Y C G C G W G R W N C K C K V A D Q S Y A. Comparison of PNV4 with TX1 (another toxin isolated from this venom, but with a molecular mass of 8.1 kDa), showed an identical N-terminal amino acid sequence for the first TX1 48 residues. This similarity could be explained by a post-translational process. Isolation of a polypeptide which induces relaxation of the corpus cavernosum muscle is certainly an important tool for the study of the mechanism of action regarding penile erection.
E. J. L. REGO, Departamento de Ciências Biológicas, Universidade do Estado da Bahia (UNEB), Km 03 da Rodovia Alagoinhas/Salvador, Cep 48100-000, Alagoinhas, Bahia.
Publication in this collection
26 Nov 1998
Date of issue