RESUMO
The bradykinin-potentiating peptides from Bothrops jararaca venom are the most potent natural inhibitors of the angiotensin-converting enzyme. The biochemical and biological features of these peptides were crucial to demonstrate the pivotal role of the angiotensin-converting enzyme in blood pressure regulation. In the present study, seven bradykinin-potentiating peptides were identified within the C-type natriuretic peptide precursor cloned from snake brain. The bradykinin-potentiating peptides deduced from the B. jararaca brain precursor are strong in vitro inhibitors of the angiotensin-converting enzyme (nanomolar range), and also potentiate the bradykinin effects in ex vivo and in vivo experiments. Two of these peptides are novel bradykinin-potentiating peptides, one of which displays high specificity toward the N-domain active site of the somatic angiotensin-converting enzyme. In situ hybridization studies revealed the presence of the bradykinin-potentiating peptides precursor mRNAs in distinct regions of the B. jararaca brain, such as the ventromedial hypothalamus, the paraventricular nuclei, the paraventricular organ, and the subcommissural organ. The biochemical and pharmacological properties of the brain bradykinin-potentiating peptides, their presence within the neuroendocrine regulator C-type natriuretic peptide precursor, and their expression in regions of the snake brain correlated to neuroendocrine functions, strongly suggest that these peptides belong to a novel class of endogenous vasoactive peptides.
Assuntos
Inibidores da Enzima Conversora de Angiotensina/farmacologia , Encéfalo/metabolismo , Peptídeo Natriurético Tipo C , Oligopeptídeos/farmacologia , Fragmentos de Peptídeos/farmacologia , Precursores de Proteínas/genética , Sequência de Aminoácidos , Inibidores da Enzima Conversora de Angiotensina/química , Animais , Bioensaio , Pressão Sanguínea/efeitos dos fármacos , Bothrops , Bradicinina/farmacologia , Química Encefálica , Sinergismo Farmacológico , Cobaias , Íleo/efeitos dos fármacos , Técnicas In Vitro , Masculino , Dados de Sequência Molecular , Contração Muscular/efeitos dos fármacos , Peptídeo Natriurético Tipo C/biossíntese , Oligopeptídeos/química , Oligopeptídeos/genética , Especificidade de Órgãos , Fragmentos de Peptídeos/química , Fragmentos de Peptídeos/genética , Precursores de Proteínas/química , Precursores de Proteínas/metabolismo , RNA Mensageiro/metabolismo , Ratos , Ratos Wistar , Análise de Sequência de DNA , Homologia de Sequência de Aminoácidos , Especificidade por SubstratoRESUMO
The bradykinin-potentiating peptides from Bothrops jararaca venom are the most potent natural inhibitors of the angiotensin-converting enzyme. The biochemical and biological features of these peptides were crucial to demonstrate the pivotal role of the angiotensin-converting enzyme in blood pressure regulation. In the present study, seven bradykinin-potentiating peptides were identified within the C-type natriuretic peptide precursor cloned from snake brain. The bradykinin-potentiating peptides deduced from the B. jararaca brain precursor are strong in vitro inhibitors of the angiotensin-converting enzyme (nanomolar range), and also potentiate the bradykinin effects in ex vivo and in vivo experiments. Two of these peptides are novel bradykinin-potentiating peptides, one of which displays high specificity toward the N-domain active site of the somatic angiotensin-converting enzyme. In situ hybridization studies revealed the presence of the bradykinin-potentiating peptides precursor mRNAs in distinct regions of the B. jararaca brain, such as the ventromedial hypothalamus, the paraventricular nuclei, the paraventricular organ, and the subcommissural organ. The biochemical and pharmacological properties of the brain bradykinin-potentiating peptides, their presence within the neuroendocrine regulator C-type natriuretic peptide precursor, and their expression in regions of the snake brain correlated to neuroendocrine functions, strongly suggest that these peptides belong to a novel class of endogenous vasoactive peptides.
