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

Three novel peptides were isolated from the venomous saliva of predatory re duviids, They were identified by mass spectrometry and HPLC analysis and co nsist of 34-36 amino acid residues. They are relatively homologous to the c alcium channel blockers omega -conotoxins from marine cone snails and belon g to the four-loop Cys scaffold structural class. Ptu1, the shortest peptid e, was chemically synthesized (sPtu1) and coeluted with its native form. Ci rcular dichroism spectra of the sPtu1 showed a high content of beta -turns similar to that of omega -conotoxins GVIA and MVIIA. Electrophysiological e xperiments demonstrated that sPtu1 reversibly blocks the N-type calcium cha nnels expressed in BHK cells. (C) 2001 Federation of European Biochemical S ocieties, Published by Elsevier Science B.V. All rights reserved.