Biogenic Manganese-Oxide Mineralization is Enhanced by an Oxidative Priming Mechanism for the Multi-Copper Oxidase, MnxEFG

Lizhi Tao, Alexandr N. Simonov, Christine A. Romano, Cristina N. Butterfield, Monika Fekete, Bradley M. Tebo, Alan M. Bond, Leone Spiccia, Lisandra L. Martin, William H. Casey

Research output: Contribution to journalArticle

7 Scopus citations

Abstract

In a natural geochemical cycle, manganese-oxide minerals (MnOx) are principally formed through a microbial process, where a putative multicopper oxidase MnxG plays an essential role. Recent success in isolating the approximately 230 kDa, enzymatically active MnxEFG protein complex, has advanced our understanding of biogenic MnOxmineralization. Here, the kinetics of MnOxformation catalyzed by MnxEFG are examined using a quartz crystal microbalance (QCM), and the first electrochemical characterization of the MnxEFG complex is reported using Fourier transformed alternating current voltammetry. The voltammetric studies undertaken using near-neutral solutions (pH 7.8) establish the apparent reversible potentials for the Type 2 Cu sites in MnxEFG immobilized on a carboxy-terminated monolayer to be in the range 0.36–0.40 V versus a normal hydrogen electrode. Oxidative priming of the MnxEFG protein complex substantially enhances the enzymatic activity, as found by in situ electrochemical QCM analysis. The biogeochemical significance of this enzyme is clear, although the role of an oxidative priming of catalytic activity might be either an evolutionary advantage or an ancient relic of primordial existence.

Original languageEnglish (US)
Pages (from-to)1346-1352
Number of pages7
JournalChemistry - A European Journal
Volume23
Issue number6
DOIs
StatePublished - Jan 1 2017

Keywords

  • Fourier transformed AC voltammetry
  • direct protein electrochemistry
  • manganese oxide mineralization
  • multi-copper oxidase activity
  • quartz crystal microbalance

ASJC Scopus subject areas

  • Catalysis
  • Organic Chemistry

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    Tao, L., Simonov, A. N., Romano, C. A., Butterfield, C. N., Fekete, M., Tebo, B. M., Bond, A. M., Spiccia, L., Martin, L. L., & Casey, W. H. (2017). Biogenic Manganese-Oxide Mineralization is Enhanced by an Oxidative Priming Mechanism for the Multi-Copper Oxidase, MnxEFG. Chemistry - A European Journal, 23(6), 1346-1352. https://doi.org/10.1002/chem.201603803