The effects of the C-terminal amidation of mastoparans on their biological actions and interactions with membrane-mimetic systems.

Polycationic peptides may present their C-termini in either amidated or acidic form; however, the effects of these conformations on the mechanisms of interaction with the membranes in general were not properly investigated up to now. Protonectarina-MP mastoparan with an either amidated or acidic C-terminus was utilized to study their interactions with anionic and zwitterionic vesicles, using measurements of dye leakage and a combination of H/D exchange and mass spectrometry to monitor peptide-membrane interactions. Mast cell degranulation, hemolysis and antibiosis assays were also performed using these peptides, and the results were correlated with the structural properties of the peptides.

Characterization of two novel polyfunctional mastoparan peptides from the venom of the social wasp Polybia paulista.

Hymenoptera venoms are complex mixtures of biochemically and pharmacologically active components such as biogenic amines, peptides and proteins. Polycationic peptides generally constitute the largest group of Hymenoptera venom toxins, and the mastoparans constitute the most abundant and important class of peptides in the venom of social wasps. These toxins are responsible for histamine release from mast cells, serotonin from platelets, and catecholamines and adenylic acids from adrenal chromafin cells.