JBIC Journal of Biological Inorganic Chemistry

, Volume 18, Issue 2, pp 175–181

Why is the molybdenum-substituted tungsten-dependent formaldehyde ferredoxin oxidoreductase not active? A quantum chemical study

Original Paper

DOI: 10.1007/s00775-012-0961-5

Cite this article as:
Liao, RZ. J Biol Inorg Chem (2013) 18: 175. doi:10.1007/s00775-012-0961-5


Formaldehyde ferredoxin oxidoreductase is a tungsten-dependent enzyme that catalyzes the oxidative degradation of formaldehyde to formic acid. The molybdenum ion can be incorporated into the active site to displace the tungsten ion, but is without activity. Density functional calculations have been employed to understand the incapacitation of the enzyme caused by molybdenum substitution. The calculations show that the enzyme with molybdenum (Mo-FOR) has higher redox potential than that with tungsten, which makes the formation of the MoVI=O complex endothermic by 14 kcal/mol. Following our previously suggested mechanism for this enzyme, the formaldehyde substrate oxidation was also investigated for Mo-FOR using the same quantum-mechanics-only model, except for the displacement of tungsten by molybdenum. The calculations demonstrate that formaldehyde oxidation occurs via a sequential two-step mechanism. Similarly to the tungsten-catalyzed reaction, the MoVI=O species performs the nucleophilic attack on the formaldehyde carbon, followed by proton transfer in concert with two-electron reduction of the metal center. The first step is rate-limiting, with a total barrier of 28.2 kcal/mol. The higher barrier is mainly due to the large energy penalty for the formation of the MoVI=O species.


Density functional calculationsFormaldehyde ferredoxin oxidoreductaseTungstenMolybdenumSelectivity

Supplementary material

775_2012_961_MOESM1_ESM.pdf (338 kb)
Supplementary material 1. Supporting information available. Cartesian coordinates for all stationary points for formaldehyde oxidation by Mo-FOR. This material is available free of charge via the Internet. (PDF 339 kb)

Copyright information

© SBIC 2012

Authors and Affiliations

  1. 1.Max-Planck-Institut für KohlenforschungMülheim an der RuhrGermany