title: Electrochemical screening of anti-microbial peptide LL-37 interaction with phospholipids.
abstract: LL-37 is an alpha-helical antimicrobial peptide of human origin. It is a 37 residue cathelicidin peptide. This paper explores the use of electrochemical methods to investigate the interaction of LL-37 with phospholipid and lipid A monolayers on a mercury drop electrode. Experiments were carried out in Dulbecco's phosphate buffered saline at pH approximately 7.6. The capacity-potential curves of the coated electrode in the presence and absence of LL-37 were measured using out-of-phase ac voltammetry. The frequency dependence of the complex impedance of the coated electrode in the presence and absence of LL-37 was estimated at -0.4 V versus Ag/AgCl 3.5 mol dm(-3) KCl. The monolayer permeability to ions was studied by following the reduction of Tl(I) to Tl(Hg) at the coated electrode. LL-37 shows no significant interaction with DOPC. However, LL-37 shows a small interaction with DOPG and lipid A within a DOPC monolayer where the monolayer permeability is marginally increased and the zero frequency capacitance (ZFC) is marginally decreased in both cases. LL-37 shows a significant interaction with a lipid A monolayer thereby decreasing the ZFC by 30%. The results concur with the known membrane active properties of LL-37 and establish this electrochemical approach as a key technique for screening peptides.
authors.affiliation: Institute for Materials Research, School of Process, Environmental and Materials Engineering, University of Leeds, LS2 9JT, UK.
authors.forename: Frances
authors.initials: F
authors.lastname: Neville
authors.forename: David
authors.initials: D
authors.lastname: Gidalevitz
authors.forename: Girish
authors.initials: G
authors.lastname: Kale
authors.forename: Andrew
authors.initials: A
authors.lastname: Nelson
mesh_terms: D023181:Antimicrobial Cationic Peptides / Q000737:chemistry*; D017097:Electric Impedance; D004563:Electrochemistry / Q000379:methods*; D008051:Lipid Bilayers / Q000737:chemistry*; D008422:Materials Testing / Q000379:methods; D010743:Phospholipids / Q000737:chemistry*; D016062:Porosity; D013057:Spectrum Analysis / Q000379:methods*; D054804:Cathelicidins
chemical_list: D023181:Antimicrobial Cationic Peptides; D008051:Lipid Bilayers; D010743:Phospholipids; D054804:Cathelicidins