TY - JOUR
T1 - Biogenic Manganese-Oxide Mineralization is Enhanced by an Oxidative Priming Mechanism for the Multi-Copper Oxidase, MnxEFG
AU - Tao, Lizhi
AU - Simonov, Alexandr N.
AU - Romano, Christine A.
AU - Butterfield, Cristina N.
AU - Fekete, Monika
AU - Tebo, Bradley M.
AU - Bond, Alan M.
AU - Spiccia, Leone
AU - Martin, Lisandra L.
AU - Casey, William H.
N1 - Publisher Copyright:
© 2017 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
PY - 2017/1/26
Y1 - 2017/1/26
N2 - 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.
AB - 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.
KW - Fourier transformed AC voltammetry
KW - direct protein electrochemistry
KW - manganese oxide mineralization
KW - multi-copper oxidase activity
KW - quartz crystal microbalance
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U2 - 10.1002/chem.201603803
DO - 10.1002/chem.201603803
M3 - Article
C2 - 27726210
AN - SCOPUS:85010737424
SN - 0947-6539
VL - 23
SP - 1346
EP - 1352
JO - Chemistry - A European Journal
JF - Chemistry - A European Journal
IS - 6
ER -