Electrochemistry
Online ISSN : 2186-2451
Print ISSN : 1344-3542
ISSN-L : 1344-3542
Articles
Effects of Elimination of α Helix Regions on Direct Electron Transfer-type Bioelectrocatalytic Properties of Copper Efflux Oxidase
Taiki ADACHIYuki KITAZUMIOsamu SHIRAITenta KAWANOKunishige KATAOKAKenji KANO
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2020 Volume 88 Issue 3 Pages 185-189

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Abstract

We investigated properties of direct electron transfer (DET)-type bioelectrocatalysis of recombinant native Copper efflux oxidase (rCueO) and its variants which lack α helices covering the electron-donating substrate-binding site (Δα5–7CueO, Δα5CueO, Δα6–7CueO, and Δα5–7+1/2α5CueO) at mesoporous carbon electrodes without pretreatment and modified with positively or negatively charged aromatic amines. Kinetic and thermodynamic parameters of the electrode reaction were obtained by analysis of steady-state catalytic waves based on a random orientation model and examined the results on the basis of the structural information of the enzymes. The data suggested that the electron transfer pathway is different from that in solution; electrons are transferred from an electrode to the T1 Cu site through the negatively charged position near the T1 Cu site in rCueO without passing through the α helix region in DET-type bioelectrocatalysis. Positively charged electrode was a suitable scaffold for DET-type reaction of rCueO. The T1 Cu site in Δα5CueO became somewhat hydrophobic and hydrophobic electrode worked as a suitable scaffold for the variant. Negatively charged electrode seems to induce unfavorable attractive orientation for DET-type reaction between the electrode and positively charged region of the CueOs on the opposite side of the T1 Cu site.

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© The Author(s) 2020. Published by ECSJ.

This is an open access article distributed under the terms of the Creative Commons Attribution 4.0 License (CC BY, http://creativecommons.org/licenses/by/4.0/), which permits unrestricted reuse of the work in any medium provided the original work is properly cited. [DOI: 10.5796/electrochemistry.20-00015].
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