We measured the current signal of the transmembrane model peptides using the barrel-stave, toroidal pore, and penetration models in order to establish a precise assignment of the channel signals. In addition, we analyzed the spike signals to estimate the membrane penetration of model cell-penetration peptides of different lengths.
Bombinin
H2 and H4 are peptides isolated from the skin of the frog Bombina variegata that exhibit antimicrobial activity against Leishmania as well as bacteria. H4 is an isomer of H2 that
has d-allo-Ile at position 2 from the N-terminus. Although
H4 exhibits higher antimicrobial activity than that of H2, the molecular
mechanism has remained unclear. In this study, we tried to reveal
the molecular mechanism in terms of lipid membrane disruption through
pore formation, using electrophysiological measurements. Based on
our experiments, we estimated the pore-forming structure, pore size,
and the kinetics in a bacteria model membrane. Stochastic analysis
of the current data indicated that peptide isomerization enables us
to accelerate the pore formation owing to the higher affinity between
the peptide and lipid membrane. Additionally, the H2/H4 mixture was
studied with 31P NMR and cross-linking experiment with
mass spectrometry. It was found that heterogeneous pore formation
with H2 and H4 was indicated. This electrophysiological approach will
likely be promising as a useful tool for analyzing the molecular mechanism
of pore-forming peptides.
This paper describes a method of hairpin DNA (hpDNA) unzipping analysis using a biological nanopore array. Various lengths of hpDNAs were captured and translocated through the nanopore and the individual duration times were monitored. The correlation between the unzipping time and the simulated hybridization energy of the duplexes was able to be modeled as first-ordered reaction. This method is one of the approach for understanding of basic biological reactions in DNA replication and RNA transcription.
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