ISBN: 978-83-60043-10-3 - eurobic9

Eurobic9, 2-6 September, 2008, Wrocław, Poland
P208. Reinvestigation of Dioxygen Activation by α-Ketoglutarate
Dependent Dioxygenase
S. Ye a , C. Riplinger a , C. Krebs b , M. Bollinger b , and F. Neese a
a Institute of Physical and Theoretical Chemistry, Bonn University, Germany
b Department of Biochemistry, Penn State University, USA
The TauD/α-ketoglutarate (α-KG)-dependent dioxygenase is a member of the superfamily of α-ketoglutaratedependent
dioxygenase, a large and diverse class of mononuclear non-heme iron enzymes that require hs-Fe(II),
α-KG and dioxygen for catalysis. The reaction mechanism for dioxygen activation in this enzyme system has
been studied by hybrid density functional theory (DFT) at septet, quintet and triplet potential energy surfaces.
The calculations showed that the dioxygen activation proceeds at the septet potential surface through only one
transition state for a concerted O-O and C-C bond cleavage, which is consistent with the experimental findings
that oxidative decarboxylation of the α-KG is the rate-limiting step. Detailed analysis of the electron pathways
for the four-electron reduction process of dioxygen provided new insights into the catalytic mechanism: Why is
only one transition state needed at the septet surface? Why can the similar process not take place at the quintet
and triplet potential surfaces? What kind of roles do the hs-Fe(II) and α-KG play for the dioxygen activation?
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