Surface evaluation techniques to characterize ?de novo? design antimicrobial peptides

MATURANA P; FELÍCIO, MÁRIO R.; MARTINEZ, M; ESPECHE, JC; GONÇALVES, S; SANTOS, NC; SEMORILE, L; MAFFIA, P; HOLLMANN, A

Buenos Aires

Congreso; Reunión Conjunta de Sociedades de Biociencias; 2017

Sociedades de Biociencias de Argentina

Conventional antibiotics are facing strong microbial resistance that has recently reached critical levels. This situation is leading to a reduced therapeutic potential of a huge proportion of antimicrobial agents currently used in the clinic. Antimicrobial peptides (AMPs) could provide the medical community with an alternative strategy to traditional antibiotics for combating microbial resistance. However, fully understand their mechanisms of action and promote the reduction of the unwanted toxicity remains as a critical step to consider these compounds to be a therapeutic promise and overcome clinical setbacks. In this context, this work focused on unravel the way of action of de novo designed AMPs by using surface evaluation techniques as Surface Pressure, Surface Plasmon Resonance (SPR) and Atomic Force Microscopy (AFM). Surface pressure results obtained well correlate the highest affinity toward negatively charged membranes with the highers CIM values. Whereas SPR technique that allows to obtain association (ka) and dissociation (kd) constants and calculate the fraction of the peptide that remains bound to the lipid membranes after dissociation (Rb), allows to dissect the kind of interactions. SPR results showed that beside the importance of a high membrane affinity, that allow the peptides reach the membrane, this Rb parameter complements the analysis and helps to clarify misinterpretations of the Kd data, confirming that also matter that peptides remained strongly bound to membranes (i.e. high Rb). Finally, by AFM we were able to visualize the effects of AMPs directly on the bacterial cells. Error and height images showed that after 1h of peptide incubation, bacteria surface was severely damaged and leakage of intracellular media was also observed. Overall, our studies focus on understanding possible relations between AMP?membrane interactions and the efficiency of these drugs, offering a rational basis for the improvement of these compounds.