Electron transfer reactions, cyanide and O-2 binding of truncated hemoglobin from Bacillus subtilis
(2013) In Electrochimica Acta 110. p.86-93- Abstract
- The truncated hemoglobin from Bacillus subtilis (trHb-Bs) possesses a surprisingly high affinity for oxygen and resistance to (auto)oxidation; its physiological role in the bacterium is not understood and may be connected with its very special redox and ligand binding reactions. Electron transfer reactions of trHb-Bs were electrochemically studied in solution and at graphite electrodes. Spectrophotometrical potentiometric titration and direct electrochemical measurements gave a heme iron redox potential of -103 +/- 4 mV and -108 +/- 2 mV vs. NHE, at pH 7, respectively. The redox potential of the heme in trHb-Bs shifted -59 mV per pH unit at pH higher than 7, consistently with a 1e(-)/1H(+) - transfer reaction. The heterogeneous rate... (More)
- The truncated hemoglobin from Bacillus subtilis (trHb-Bs) possesses a surprisingly high affinity for oxygen and resistance to (auto)oxidation; its physiological role in the bacterium is not understood and may be connected with its very special redox and ligand binding reactions. Electron transfer reactions of trHb-Bs were electrochemically studied in solution and at graphite electrodes. Spectrophotometrical potentiometric titration and direct electrochemical measurements gave a heme iron redox potential of -103 +/- 4 mV and -108 +/- 2 mV vs. NHE, at pH 7, respectively. The redox potential of the heme in trHb-Bs shifted -59 mV per pH unit at pH higher than 7, consistently with a 1e(-)/1H(+) - transfer reaction. The heterogeneous rate constant k(s), for a quasi-reversible 1e(-)-1H(+) - transfer reaction between graphite and trHb-Bs was 10.1 +/- 2.3 s(-1). Upon reversible cyanide binding the ks doubled, while the redox potential of heme shifted 21 mV negatively, presumably reflecting changes in redox activity and in vivo signaling functions of trHb-Bs associated with ligand binding Bioelectrocatalytic reduction of O-2 catalyzed by trHb-Bs was one of the most efficient hitherto reported for Hbs, with an apparent catalytic rate constant, k(cat), of 56 +/- 6s(-1). The results obtained are of particular interest for applications of trHb in environmental biosensing and toxicity screening. (C) 2013 Elsevier Ltd. All rights reserved. (Less)
Please use this url to cite or link to this publication:
https://lup.lub.lu.se/record/4320128
- author
- Fernandez, Esther ; Larsson, Jonas LU ; McLean, Kirsty J. ; Munro, Andrew W. ; Gorton, Lo LU ; von Wachenfeldt, Claes LU and Ferapontova, Elena E.
- organization
- publishing date
- 2013
- type
- Contribution to journal
- publication status
- published
- subject
- keywords
- Heme proteins, Electron transfer, Bacillus subtilis truncated, hemoglobin, Bioelectrocatalysis, Ligand binding
- in
- Electrochimica Acta
- volume
- 110
- pages
- 86 - 93
- publisher
- Pergamon Press Ltd.
- external identifiers
-
- wos:000329530300013
- scopus:84888285980
- ISSN
- 0013-4686
- DOI
- 10.1016/j.electacta.2013.03.025
- language
- English
- LU publication?
- yes
- id
- ff6dd6a1-ef2f-4f5f-bab4-b29c34e259f9 (old id 4320128)
- date added to LUP
- 2016-04-01 09:48:30
- date last changed
- 2024-03-09 03:58:47
@article{ff6dd6a1-ef2f-4f5f-bab4-b29c34e259f9,
abstract = {{The truncated hemoglobin from Bacillus subtilis (trHb-Bs) possesses a surprisingly high affinity for oxygen and resistance to (auto)oxidation; its physiological role in the bacterium is not understood and may be connected with its very special redox and ligand binding reactions. Electron transfer reactions of trHb-Bs were electrochemically studied in solution and at graphite electrodes. Spectrophotometrical potentiometric titration and direct electrochemical measurements gave a heme iron redox potential of -103 +/- 4 mV and -108 +/- 2 mV vs. NHE, at pH 7, respectively. The redox potential of the heme in trHb-Bs shifted -59 mV per pH unit at pH higher than 7, consistently with a 1e(-)/1H(+) - transfer reaction. The heterogeneous rate constant k(s), for a quasi-reversible 1e(-)-1H(+) - transfer reaction between graphite and trHb-Bs was 10.1 +/- 2.3 s(-1). Upon reversible cyanide binding the ks doubled, while the redox potential of heme shifted 21 mV negatively, presumably reflecting changes in redox activity and in vivo signaling functions of trHb-Bs associated with ligand binding Bioelectrocatalytic reduction of O-2 catalyzed by trHb-Bs was one of the most efficient hitherto reported for Hbs, with an apparent catalytic rate constant, k(cat), of 56 +/- 6s(-1). The results obtained are of particular interest for applications of trHb in environmental biosensing and toxicity screening. (C) 2013 Elsevier Ltd. All rights reserved.}},
author = {{Fernandez, Esther and Larsson, Jonas and McLean, Kirsty J. and Munro, Andrew W. and Gorton, Lo and von Wachenfeldt, Claes and Ferapontova, Elena E.}},
issn = {{0013-4686}},
keywords = {{Heme proteins; Electron transfer; Bacillus subtilis truncated; hemoglobin; Bioelectrocatalysis; Ligand binding}},
language = {{eng}},
pages = {{86--93}},
publisher = {{Pergamon Press Ltd.}},
series = {{Electrochimica Acta}},
title = {{Electron transfer reactions, cyanide and O-2 binding of truncated hemoglobin from Bacillus subtilis}},
url = {{http://dx.doi.org/10.1016/j.electacta.2013.03.025}},
doi = {{10.1016/j.electacta.2013.03.025}},
volume = {{110}},
year = {{2013}},
}