Facultatea de Fizică
Universitatea "Al.I.Cuza" Iaşi
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| Titlu: Kinetics of pore formation by selected antimicrobial peptides monitored through a calcein release assay |
| Autori: Irina Şchiopu1, Aurelia Apetrei1, Tudor Luchian1 |
| Afiliere: 1Department of Physics, Laboratory of Biophysics and Medical Physics, “Al. I. Cuza” University, Iaşi, Romania |
| Abstract: Antimicrobial peptides (AMPs) are an important component of the immune system, and have generated considerable interest as a potential new class of antibiotics. The biological activity of AMPs is strongly influenced by peptide-membrane interactions, however for many of these peptides the molecular details of how they disrupt and/or translocate across target membranes are not fully understood. The action of antimicrobial peptides induces membrane defects such as phase separation or membrane thinning, pore formation, promotion of nonlamellar lipid structure or bilayer disruption, depending on the molecular properties of both peptide and lipid. These pathways are variously termed transmembrane pores, toroidal pores or channel aggregates. In this study we employed a calcein release assay from small unilamellar vesicles (SUVs) in order to follow the kinetics of pore formation of some selected antimicrobial peptides. Oligomerization of the peptide monomers that adsorb at the interface of the lipid membrane and insert into the bilayer hydrophobic core leads to pore formation which enables calcein trapped inside the vesicles at a self quenching concentration to be released in the outer environment. The calcein-filled vesicles were separated from unencapsulated calcein by gel filtration chromatography with a Sephadex G-25 column. The increase in fluorescence emission of calcein can be thus life-time monitored to give qualitative and quantitative insights on the kinetics of pore formation by the selected antimicrobial peptides. We show that the process is concentration dependent and is influenced by the lipid composition of the vesicles.
Loraine Silvestro et al., The Concentration-Dependent Membrane Activity of Cecropin A, Biochemistry 1997, 36, 11452-11460; |
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