Novel peptides from assassin bugs (Hemiptera: Reduviidae):: isolation, chemical and biological characterization

Three novel peptides were isolated from the venomous saliva of predatory reduviids, They were identified by mass spectrometry and HPLC analysis and consist of 34-36 amino acid residues. They are relatively homologous to the calcium channel blockers omega -conotoxins from marine cone snails and belong to the four-loop Cys scaffold structural class. Ptu1, the shortest peptide, was chemically synthesized (sPtu1) and coeluted with its native form. Circular dichroism spectra of the sPtu1 showed a high content of beta -turns similar to that of omega -conotoxins GVIA and MVIIA. Electrophysiological experiments demonstrated that sPtu1 reversibly blocks the N-type calcium channels expressed in BHK cells. (C) 2001 Federation of European Biochemical Societies, Published by Elsevier Science B.V. All rights reserved.