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Issue 13, 2017
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Structure, electrocatalysis and dynamics of immobilized cytochrome PccH and its microperoxidase

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Abstract

Geobacter sulfurreducens cells have the ability to exchange electrons with conductive materials, and the periplasmic cytochrome PccH plays an essential role in the direct electrode-to-cell electron transfer in this bacterium. It has atypically low redox potential and unique structural features that differ from those observed in other c-type cytochromes. We report surface enhanced resonance Raman spectroscopic and electrochemical characterization of the immobilized PccH, together with molecular dynamics simulations that allow for the rationalization of experimental observations. Upon attachment to electrodes functionalized with partially or fully hydrophobic self-assembled monolayers, PccH displays a distribution of native and non-native heme spin configurations, similar to those observed in horse heart cytochrome c. The native structural and thermodynamic features of PccH are preserved upon attachment mixed hydrophobic (–CH3/–NH2) surfaces, while pure –OH, –NH2 and –COOH surfaces do not provide suitable platforms for its adsorption, indicating that its still unknown physiological redox partner might be membrane integrated. Neither of the employed immobilization strategies results in electrocatalytically active PccH capable of the reduction of hydrogen peroxide. Pseudoperoxidase activity is observed in immobilized microperoxidase, which is enzymatically produced from PccH and spectroscopically characterized. Further improvement of PccH microperoxidase stability is required for its application in electrochemical biosensing of hydrogen peroxide.

Graphical abstract: Structure, electrocatalysis and dynamics of immobilized cytochrome PccH and its microperoxidase

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Publication details

The article was received on 07 Dec 2016, accepted on 06 Mar 2017 and first published on 06 Mar 2017


Article type: Paper
DOI: 10.1039/C6CP08361G
Citation: Phys. Chem. Chem. Phys., 2017,19, 8908-8918
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    Structure, electrocatalysis and dynamics of immobilized cytochrome PccH and its microperoxidase

    C. M. Silveira, M. A. Castro, J. M. Dantas, C. Salgueiro, D. H. Murgida and S. Todorovic, Phys. Chem. Chem. Phys., 2017, 19, 8908
    DOI: 10.1039/C6CP08361G

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