Abstract
The dynamics of manganese solid formation (as MnOx) by the multicopper oxidase (MCO)-containing Mnx protein complex were examined by electron paramagnetic resonance (EPR) spectroscopy. Continuous-wave (CW) EPR spectra of samples of Mnx, prepared in atmosphere and then reacted with Mn(II) for times ranging from 7 to 600 s, indicate rapid oxidation of the substrate manganese (with two-phase pseudo-first-order kinetics modeled using rate coefficients of: k1obs = 0.205 ± 0.001 s-1 and k2obs = 0.019 ± 0.001 s-1). This process occurs on approximately the same time scale as in vitro solid MnOx formation when there is a large excess of Mn(II). We also found CW and pulse EPR spectroscopic evidence for at least three classes of Mn(II)-containing species in the reaction mixtures: (i) aqueous Mn(II), (ii) a specifically bound mononuclear Mn(II) ion coordinated to the Mnx complex by one nitrogenous ligand, and (iii) a weakly exchange-coupled dimeric Mn(II) species. These findings provide new insights into the molecular mechanism of manganese mineralization.
Original language | English (US) |
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Pages (from-to) | 10563-10575 |
Number of pages | 13 |
Journal | Journal of the American Chemical Society |
Volume | 137 |
Issue number | 33 |
DOIs | |
State | Published - Aug 5 2015 |
Externally published | Yes |
ASJC Scopus subject areas
- Catalysis
- General Chemistry
- Biochemistry
- Colloid and Surface Chemistry