Switchable Redox Chemistry of the Hexameric Tyrosine-Coordinated Heme Protein

Kielb P, Utesch T, Kozuch J, Jeoung JH, Dobbek H, Mroginski MA, Hildebrandt P, Weidinger IM (2017)

Publication Type: Journal article

Publication year: 2017

Journal

Journal of Physical Chemistry B American Chemical Society

Book Volume: 121

Pages Range: 3955-3964

Journal Issue: 16

DOI: 10.1021/acs.jpcb.7b01286

Abstract

Hexameric tyrosine-coordinated heme protein HTHP from Silicibacter pomeroyi has been shown to exhibit peroxidase- and catalase-like activity. In the present study, detailed spectroscopic and electrochemical investigations were performed to analyze the redox properties and active site structure of HTHP. Potentiometric titration of HTHP in solution revealed a single redox transition at -0.54 V (vs Ag/AgCl), indicating six structurally identical tyrosine coordinates hemes. Cyclic voltammetry (CV) of immobilized HTHP afforded a distinctly more positive redox potential (-0.17 V) but failed to detect a transition at -0.54 V. Conversely, surface enhanced RR (SERR) spectroscopy provided evidence for both high- and low-potential transitions and for a partial loss of heme in the reduced state. The high-potential CV-active redox transition is attributed to the hemes of the barrel-shaped HTHP in a wheel-like orientation on the surface. Supported by coarse-grained simulations and SERR spectroscopy, the majority of HTHP is concluded to adopt a reverse-disc orientation, accounting for the low-potential transition. In view of the striking similarity of HTHP to the heme carriers HasA or HmbR regarding redox potential, Fe-Tyr ligation, and heme release, we propose heme transport as an alternative or additional function.

Involved external institutions

Technische Universität Berlin DE Germany (DE) Humboldt-Universität zu Berlin DE Germany (DE) Technische Universität Dresden DE Germany (DE)

How to cite

APA:

Kielb, P., Utesch, T., Kozuch, J., Jeoung, J.-H., Dobbek, H., Mroginski, M.A.,... Weidinger, I.M. (2017). Switchable Redox Chemistry of the Hexameric Tyrosine-Coordinated Heme Protein. Journal of Physical Chemistry B, 121(16), 3955-3964. https://doi.org/10.1021/acs.jpcb.7b01286

MLA:

Kielb, Patrycja, et al. "Switchable Redox Chemistry of the Hexameric Tyrosine-Coordinated Heme Protein." Journal of Physical Chemistry B 121.16 (2017): 3955-3964.

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