Table of Contents
To view the fulltext, log-in or choose pay-per-view options:
Get Access

A Possible Role for Iron-Sulfur Cluster N2 in Proton Translocation by the NADH:Ubiquinone Oxidoreductase (Complex I)

Flemming D.a · Stolpe S.a · Schneider D.a · Hellwig P.b · Friedrich T.a
aInstitut für Organische Chemie und Biochemie, Albert-Ludwigs-Universität Freiburg, Freiburg, and bInstitut für Biophysik, Johann-Wolfgang-Goethe-Universität, Frankfurt am Main, Germany J Mol Microbiol Biotechnol 2005;10:208–222 (DOI:10.1159/000091566)


The proton-pumping NADH:ubiquinone oxidoreductase, the respiratory complex I, couples the transfer of electrons from NADH to ubiquinone with the translocation of protons across the membrane. The enzyme mechanism is still unknown due to the lack of a high-resolution structure and its complicated composition. The complex from Escherichia coli is made up of 13 subunits called NuoA through NuoN and contains one FMN and nine iron-sulfur (Fe/S) clusters as redox groups. The pH dependence of the midpoint redox potential of the Fe/S cluster named N2 and its spin-spin interaction with ubiquinone radicals made it an ideal candidate for a key component in redox-driven proton translocation. During the past years we have assigned the subunit localization of cluster N2 to subunit NuoB by site-directed mutagenesis and predicted its ligation by molecular simulation. Redox-induced FT-IR spectroscopy has shown that its redox reaction is accompanied by the protonation and deprotonation of individual amino acid residues. These residues have been identified by site-directed mutagenesis. The enzyme catalytic activity depends on the presence of cluster N2 and is coupled with major conformational changes. From these data a model for redox-induced conformation-driven proton translocation has been derived.


Individual Users: Register with Karger Login Information

Please create your User ID & Password

Contact Information

I have read the Karger Terms and Conditions and agree.

Pay-per-View Options
Direct payment This item at the regular price: USD 38.00
Payment from account With a Karger Pay-per-View account (down payment USD 150) you profit from a special rate for this and other single items.
This item at the discounted price: USD 26.50