Document Detail

FT-IR spectroscopic characterization of NADH:ubiquinone oxidoreductase (complex I) from Escherichia coli: oxidation of FeS cluster N2 is coupled with the protonation of an aspartate or glutamate side chain.
MedLine Citation:
PMID:  10978175     Owner:  NLM     Status:  MEDLINE    
The proton-pumping NADH:ubiquinone oxidoreductase, also called complex I, is the first energy-transducing complex of many respiratory chains. It couples the transfer of electrons from NADH to ubiquinone with the translocation of protons across the membrane. One FMN and up to nine iron-sulfur (FeS) clusters participate in the redox reaction. So far, complex I has been described mainly by means of EPR- and UV-vis spectroscopy. Here, we report for the first time an infrared spectroscopic characterization of complex I. Electrochemically induced FT-IR difference spectra of complex I from Escherichia coli and of the NADH dehydrogenase fragment of this complex were obtained for critical potential steps. The spectral contributions of the FMN in both preparations were derived from a comparison using model compounds and turned out to be unexpectedly small. Furthermore, the FT-IR difference spectra reveal that the redox transitions of the FMN and of the FeS clusters induce strong reorganizations of the polypeptide backbone. Additional signals in the spectra of complex I reflect contributions induced by the redox transition of the high-potential FeS cluster N2 which is not present in the NADH dehydrogenase fragment. Part of these signals are attributed to the reorganization of protonated/deprotonated Asp or Glu side chains. On the basis of these data we discuss the role of N2 for proton translocation of complex I.
P Hellwig; D Scheide; S Bungert; W Mäntele; T Friedrich
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Publication Detail:
Type:  Journal Article; Research Support, Non-U.S. Gov't    
Journal Detail:
Title:  Biochemistry     Volume:  39     ISSN:  0006-2960     ISO Abbreviation:  Biochemistry     Publication Date:  2000 Sep 
Date Detail:
Created Date:  2000-09-28     Completed Date:  2000-09-28     Revised Date:  2006-11-15    
Medline Journal Info:
Nlm Unique ID:  0370623     Medline TA:  Biochemistry     Country:  UNITED STATES    
Other Details:
Languages:  eng     Pagination:  10884-91     Citation Subset:  IM    
Institut für Biophysik, Johann-Wolfgang-Goethe-Universität Theodor-Stern-Kai 7, Haus 74, 60590 Frankfurt/M., Germany.
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MeSH Terms
Alkanesulfonic Acids / chemistry
Aspartic Acid / chemistry*,  metabolism
Electron Transport Complex I
Escherichia coli / enzymology*
Glutamic Acid / chemistry*,  metabolism
Iron-Sulfur Proteins / chemistry*,  metabolism
Models, Chemical
Morpholines / chemistry
NADH, NADPH Oxidoreductases / chemistry*,  metabolism
Peptide Fragments / chemistry,  metabolism
Proton Pumps / chemistry*,  metabolism
Spectrophotometry, Ultraviolet
Spectroscopy, Fourier Transform Infrared / methods
Reg. No./Substance:
0/Alkanesulfonic Acids; 0/Buffers; 0/Iron-Sulfur Proteins; 0/Morpholines; 0/Peptide Fragments; 0/Proton Pumps; 4432-31-9/2-(N-morpholino)ethanesulfonic acid; 56-84-8/Aspartic Acid; 56-86-0/Glutamic Acid; EC 1.6.-/NADH, NADPH Oxidoreductases; EC Transport Complex I

From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine

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