Specific Detection of PE-Included Vesicles Using Cyclic Voltammetry

Yeseul Park,Jin-Won Park

doi:10.3390/app11083660

Yeseul Park, Jin-Won Park

Open Access

https://doi.org/10.3390/app11083660

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Abstract

The binding between cinnamycin and the phosphatidylethanolamine (PE)-included vesicles was monitored using cyclic voltammetry (CV) measurements and interpreted in terms of the composition of the vesicles and the monolayer binding site. The monolayer was composed of pure 11-mercapto-1-undecanol (MUD) to 90% MUD/10% 16-mercaptohexadecanoic acid (MHA) on a gold surface. Cinnamycin was immobilized on each monolayer. The vesicles, prepared at the desired ratio of the phospholipids, were injected on the cinnamycin-immobilized surface. CV experiments were performed for each step. For the pure-dipalmitoylphosphatidyl-choline (DPPC) vesicles on all of monolayers and the DPPC/dipalmitoylphosphatidyl-ethanolamine (DPPE) vesicles on the pure-MUD monolayer, the electric property of the surface was little changed. However, the vesicles made with 90% DPPC/10% DPPE on the monolayer prepared with 99% MUD/1% MHA to 90% MUD/10% MHA showed a consistent decrease in the CV response. Additionally, in the 95% DPPC/5% DPPE vesicles and the 99.5% MUD/0.5% MHA monolayer, variances in the responses were observed.

Highlights

Cinnamycin, a 19-amino acid tetracyclic peptide, is a globular electrically neutral peptide capable of forming an equimolecular complex with phosphatidylethanolamine (PE) [1,2]
The decrease seemed to be caused by the vesicles’ immobilization on the electrode surface, which seemed to prohibit the electron transfer. These results indicated that the mercaptohexadecanoic acid (MHA) provided the site for the cinnamycin immobilization, as expected from the previous research [28]
The specific binding between the cinnamycin and the PE-included vesicles was characterized with cyclic voltammetry (CV) measurements

Summary

Introduction

Cinnamycin, a 19-amino acid tetracyclic peptide, is a globular electrically neutral peptide capable of forming an equimolecular complex with phosphatidylethanolamine (PE) [1,2]. The specific formation is generated due to its unique structure: most of the hydrophobic amino acids are positioned at one side of the peptide, whereas the hydrophilic one is located on the other side. Both the headgroup and the hydrocarbon chains of PE are crucial for interaction with the peptide [3]. The specificity has led the cinnamycin to be used for the investigation of PE-related mechanisms such as apoptosis, cell division, migration and tumor vasculature [4,5,6,7,8] This peptide has been considered as a potential probe for disrupting PE-containing membranes, such as those of cancer cells and bacteria, and an alternative treatment for atherosclerosis [9,10]. The physical characteristics of its specificity, i.e., binding affinity, thermodynamic properties and structural changes, have been investigated using enzymelinked immuno-sorbent assay (ELISA), isothermal titration calorimetry, small-angle X-ray scattering, transmission electron microscopy and surface plasmon resonance [2,11,12,13]

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