1. Biochemistry and Biophysics Laboratory, Butantan Institute, Av. Vital Brazil, 1500, São Paulo, SP, CEP 05503-900, Brazil;2. Pharmacology Laboratory, Butantan Institute, Av. Vital Brazil, 1500, São Paulo, SP, CEP 05503-900, Brazil
Abstract:
Incubation of plasma from the snake Crotalus durissus terrificus (CDTP) with trypsin generated two hypotensive peptides. The primary structure of the peptides was established for two sequences as: (Ser – Ile – Pro – Gln – Ala – Pro – Thr – Ser – Asn – Leu – Ile – Glu – Ala – Thr – Lys) and (Lys – Pro – Asp – Ala – Asn – Gln – Val – Leu – Ile – Gln – Val – Ile – Gly – Val). These peptides display homology with fragments of albumin from Trimeresurus flavoviridis. Bolus intra-arterial injection of the purified or the synthetic peptide produced a strong and sustained vasopressor response in the anaesthetized snake (CDT) and rats (Wistar); this hypotensive effect was also potentiated by captopril–an angiotensin-converting (0.1 mg/kg) enzyme inhibitor.