Universität zu Köln

Kalimuthu, Palraj, Belaidi, Abdel A., Schwarz, Guenter ORCID: 0000-0002-2118-9338 and Bernhardt, Paul V. (2017). Mediated Catalytic Voltammetry of Holo and Heme-Free Human Sulfite Oxidases. ChemElectroChem, 4 (4). S. 947 - 957. WEINHEIM: WILEY-V C H VERLAG GMBH. ISSN 2196-0216

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Abstract

Herein, we report the electrocatalytic voltammetry of holo and heme-free human sulfite oxidase (HSO) mediated by the synthetic iron complexes 1,2-bis(1,4,7-triaza-1-cyclononyl)ethane iron(III) bromide, ([Fe(dtne)]Br-3.3H(2)O), potassium ferricyanide (K-3[Fe(CN)(6)]), and ferrocene methanol (FM) at a 5-(4-pyridinyl)-1,3,4-oxadiazole-2-thiol (Hpyt) modified gold working electrode. Holo HSO contains two electroactive redox cofactors, comprising a mostly negatively charged cyt b(5) (heme) domain and a Mo cofactor (Moco) domain (the site of sulfite oxidation), where the surface near the active site is positively charged. We anticipated different catalytic voltammetry based on either repulsive or attractive electrostatic interactions between the holo or heme-free enzymes and the positively or negatively charged redox mediators. Both holo and heme-free HSO experimental catalytic voltammetry has been modeled by using electrochemical simulation across a range of sweep rates and concentrations of substrate and both positive and negatively charged electron acceptors ([Fe(dtne)](3+), [Fe(CN)(6)](3-) and FM+), which provides new insights into the kinetics of the HSO catalytic mechanism. These mediator complexes have almost the same redox potential (all lying in the range +415 to +430mV vs. NHE) and, thus, deliver the same driving force for electron transfer with the Mo cofactor. However, differences in the electrostatic affinities between HSO and the mediator have a significant influence on the electrocatalytic response.

Item Type:	Journal Article
Creators:	Creators Email ORCID ORCID Put Code Kalimuthu, Palraj UNSPECIFIED UNSPECIFIED UNSPECIFIED Belaidi, Abdel A. UNSPECIFIED UNSPECIFIED UNSPECIFIED Schwarz, Guenter UNSPECIFIED orcid.org/0000-0002-2118-9338 UNSPECIFIED Bernhardt, Paul V. UNSPECIFIED UNSPECIFIED UNSPECIFIED
URN:	urn:nbn:de:hbz:38-234921
DOI:	10.1002/celc.201600685
Journal or Publication Title:	ChemElectroChem
Volume:	4
Number:	4
Page Range:	S. 947 - 957
Date:	2017
Publisher:	WILEY-V C H VERLAG GMBH
Place of Publication:	WEINHEIM
ISSN:	2196-0216
Language:	English
Faculty:	Faculty of Mathematics and Natural Sciences
Divisions:	Faculty of Mathematics and Natural Sciences > Department of Chemistry > Institute of Biochemistry
Subjects:	no entry
Uncontrolled Keywords:	Keywords Language INTRAMOLECULAR ELECTRON-TRANSFER; CYTOCHROME B(5); SAM FORMATION; MOLYBDENUM; ELECTROCHEMISTRY; GOLD; DEHYDROGENASE; DOMAIN; NANOPARTICLES; DEFICIENCY Multiple languages Electrochemistry Multiple languages
Refereed:	Yes
URI:	http://kups.ub.uni-koeln.de/id/eprint/23492