Crystal Structure of Naphthalene Dioxygenase: Side-on Binding of Dioxygen to Iron
Andreas Karlsson,1
Juanito V. Parales,2
Rebecca E. Parales,2
David T. Gibson,2
Hans Eklund,1
S. Ramaswamy3*
Binding of oxygen to iron is exploited in several
biological and chemical processes. Although computational and
spectroscopic results have suggested side-on binding, only end-on
binding of oxygen to iron has been observed in crystal structures. We
have determined structures of naphthalene dioxygenase that show a
molecular oxygen species bound to the mononuclear iron in a side-on
fashion. In a complex with substrate and dioxygen, the dioxygen
molecule is lined up for an attack on the double bond of the aromatic
substrate. The structures reported here provide the basis for a
reaction mechanism and for the high stereospecificity of the reaction
catalyzed by naphthalene dioxygenase.
1 Department of Molecular Biology, Swedish
University of Agricultural Sciences, Box 590, Biomedical Center, 75124 Uppsala, Sweden.
2 Department of Microbiology and
Center for Biocatalysis and Bioprocessing,
3 Department of Biochemistry, University of Iowa,
Iowa City, IA 52242, USA.
*
To whom correspondence should be addressed. E-mail:
s-ramaswamy{at}uiowa.edu
