Journal
LANGMUIR
Volume 28, Issue 49, Pages 17079-17091Publisher
AMER CHEMICAL SOC
DOI: 10.1021/la303782d
Keywords
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Funding
- [POSDRU/89/1.5/S/49944]
- [POSDRU/89/1.5/S/63663]
- [PN-II-ID-PCCE-2011-2-0027]
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Metal ions binding exert a crucial influence upon the aggregation properties and stability of peptides, and the propensity of folding in various substates. Herein, we demonstrate the use of the alpha-HL protein as a powerful nanoscopic tool to probe Cu2+-triggered physicochemical changes of a 20 aminoacids long, antimicrobial-derived chimera peptide with a His residue as metal-binding site, and simultaneously dissect the kinetics of the free- and Cu2+-bound peptide interaction to the a-HL pore. Combining single-molecule electrophysiology on reconstituted lipid membranes and fluorescence spectroscopy, we show that the association rate constant between the alpha-HL pore and a Cu2+-free peptide is higher than that of a Cu2+-complexed peptide. We posit that mainly due to conformational changes induced by the Cu2+ on the peptide, the resulting complex encounters a higher energy barrier toward its association with the protein pore, stemming most likely from an extra entropy cost needed to fit the Cu2+-complexed peptide within the alpha-HL lumen region. The lower dissociation rate constant of the Cu2+-complexed peptide from alpha-HL pore, as compared to that of Cu2+-free peptide, supports the existence of a deeper free energy well for the protein interaction with a Cu2+-complexed peptide, which may be indicative of specific Cu2+-mediated contributions to the binding of the Cu2+-complexed peptide within the pore lumen. bound
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