The Interfacial Properties of the Peptide Polybia-Mp1 and its Interaction with DPPC are Modulated by Lateral Electrostatic Attractions

DAYANE S. ALVARES; MARIA LAURA FANANI; JOAO RUGGIERO NETO; NATALIA WILKE

BIOCHIMICA ET BIOPHYSICA ACTA-BIOMEMBRANES

ELSEVIER SCIENCE BV

Lugar: Amsterdam; Año: 2016 vol. 1858 p. 393 - 402

0005-2736

Polybia-MP1 (IDWKKLLDAAKQIL-NH2), extracted from the Brazilian wasp Polybia paulista, exhibits a broad-spectrum bactericidal activity without being hemolytic and cytotoxic. In the present study, we analyzed the surface properties of the peptide and its interaction with DPPC in Langmuir monolayers. Polybia-MP1 formed stable monolayers, with lateral areas and surface potential values suggesting mostly -helical structure. The peptide occupied smaller areas on pure water compared to salt solutions as well as on acidic and basic ones. Furthermore, only on pure water, DPPC and MP1 co-crystalized forming branched domains, while on subphases with high salt concentrations or at acidic or basic conditions, the peptide was excluded from the domains. The results indicate that, on pure water, attractive electrostatic interactions between peptides were present, and the peptides were able to get closer to each other and to interact with DPPC. We suggest that the residues responsible of the peptide-peptide attraction are the anionic aspartic acids and the cationic lysines, which form a salt bridge, leading to oriented interactions in the crystal and thereby to branched domains. For this peptide, the balance between total attractive and repulsive interactions may be finely tuned by the aqueous ionic strength and pH. Since the described effect is related with lysines and aspartic acids, similar effects may also happen in other peptides with similar sequences.