Electrochemical signature of hen egg white lysozyme at the glycerol-modified liquid-liquid interface

Abstract

Electrochemical characterization of hen egg white lysozyme (HEWL) at a glycerolmodified interface between two immiscible electrolyte solutions (ITIES) was conducted using a microporous silicon membrane-supported gelled-1,6-dichlorohexane|water-glycerol interface. The electrochemical response of HEWL under these conditions is of interest for the system's potential application to the formation of isorefractive emulsified-ITIES, which offer practical opportunities for spectrophotometric analysis of interfacial processes. Importantly, the voltammetric signature for HEWL seen under glycerol-rich conditions was similar but with some differences from that for glycerol-free conditions. Specifically, the potential at which facilitated transfer of the organic phase electrolyte anion tetrakis-(4chlorophenyl) borate (TPBCl-) occurred was shifted to lower potential with increasing glycerol concentration. However, features in the voltammetry associated with adsorption/desorption processes were observed to remain constant. The simple ion transfer response of tetraethylammonium cations (TEA +) at the same glycerolmodified ITIES provides insight into the nature of changes that determine the atypical HEWL signature. Lower ion transfer current with respect to increasing glycerol concentration and a shift in transfer potential were the key findings here. The results indicate that the electrochemistry which determines the HEWL signature is similar in environments that are rich in glycerol or purely aqueous.

Defined Ion-Transfer Voltammetry of a Single Microdroplet at a Polarized Liquid/Liquid Interface

“…Therefore, the multivalent ion transfer behaviors by this approach have also been attempted to investigate. However, previous studies have shown that the transfer behaviors of multivalent biopolymers, such as some proteins, tend to follow an adsorption/transfer behavior at the L/L interface, − which is significantly different from the behaviors of monovalent ions. This effect probably implied that the protein tended to form ion pairs with the anti-ions in the organic phase and adsorbed on one side of the interface.…”