REDOX CHEMISTRY OF BIOLOGICAL TUNGSTEN - AN EPR STUDY OF THE ALDEHYDEOXIDOREDUCTASE FROM PYROCOCCUS-FURIOSUS

Citation
Af. Arendsen et al., REDOX CHEMISTRY OF BIOLOGICAL TUNGSTEN - AN EPR STUDY OF THE ALDEHYDEOXIDOREDUCTASE FROM PYROCOCCUS-FURIOSUS, JBIC. Journal of biological inorganic chemistry, 1(4), 1996, pp. 292-296
Citations number
23
Categorie Soggetti
Biology,"Chemistry Inorganic & Nuclear
ISSN journal
09498257
Volume
1
Issue
4
Year of publication
1996
Pages
292 - 296
Database
ISI
SICI code
0949-8257(1996)1:4<292:RCOBT->2.0.ZU;2-T
Abstract
Aldehyde:ferredoxin oxidoreductase (AOR) from the hyperthermophilic ar chaeon Pyrococcus furiosus is a homodimeric protein. Each subunit carr ies one [4Fe-4S] cubane and a novel tungsten cofactor containing two p terins. A single iron atom bridges between the subunits. AOR has previ ously been studied with EPR spectroscopy in an inactive form known as the red tungsten protein (RTP): reduced RTP exhibits complex EPR inter action signals. We have now investigated the active enzyme AOR with EP R, and we have found an S = 1/2 plus S = 3/2 spin mixture from a non-i nteracting [4Fe-4S](1+) cluster in the reduced enzyme. Oxidized AOR af fords EPR signals typical for W(V) with g-values of 1.982, 1.953, and 1.885. The W(V) signals disappear at a reduction potential E(m,7.5) of + 180 mV. This unexpectedly high value indicates that the active-site redox chemistry is based on the pterin part of the cofactor.