EPR and Mössbauer studies of benzoyl-CoA reductase.
J Biol Chem
; 275(41): 31857-68, 2000 Oct 13.
Article
em En
| MEDLINE
| ID: mdl-10903310
ABSTRACT
Benzoyl-CoA reductase catalyzes the two-electron transfer from a reduced ferredoxin to the aromatic ring of benzoyl-CoA; this reaction is coupled to stoichiometrical ATP hydrolysis. A very low reduction potential (less than -1 V) is required for the first electron transfer to the aromatic ring. In this work the nature of the redox centers of purified benzoyl-CoA reductase from Thauera aromatica was studied by EPR and Mössbauer spectroscopy. The results obtained indicated the presence of three [4Fe-4S] clusters. Redox titration studies revealed that the reduction potentials of all three clusters were below -500 mV. The previously reported S = 7/2 state of the enzyme during benzoyl-CoA-independent ATPase activity (Boll, M., Albracht, S. J. P., and Fuchs, G. (1997) Eur. J. Biochem. 244, 840-851) was confirmed by Mössbauer spectroscopy. Inactivation by oxygen was associated with the irreversible conversion of part of the [4Fe-4S] clusters to [3Fe-4S] clusters. Acetylene stimulated the benzoyl-CoA-independent ATPase activity and induced novel EPR signals with g(av) >2. The presence of simple cubane clusters in benzoyl-CoA reductase as the sole redox-active metal centers demonstrates novel aspects of [4Fe-4S] clusters since they adopt the role of elemental sodium or lithium which are used as electron donors in the analogous chemical Birch reduction of aromatic rings.
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Coleções:
01-internacional
Base de dados:
MEDLINE
Assunto principal:
Oxirredutases
/
Thauera
/
Oxirredutases atuantes sobre Doadores de Grupo CH-CH
/
Proteínas Ferro-Enxofre
Idioma:
En
Revista:
J Biol Chem
Ano de publicação:
2000
Tipo de documento:
Article
País de afiliação:
Reino Unido