Low-spin sulfite reductases: A new homologous group of non-heme iron-siroheme proteins in anaerobic bacteria

I. Moura, A. R. Lino, José J. G. Moura, A. V. Xavier, G. Fauque, H. D. Peck, J. LeGall

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35 Citations (Scopus)

Abstract

Two new low molecular weight proteins with sulfite reductase activity, isolated from Methanosarcina barkeri (DSM 800) and Desulfuromonas acetoxidans (strain 5071), were studied by EPR and optical spectroscopic techniques. Both proteins have visible spectra similar to that of the low-spin sulfite reductase of Desu1fovibrio vulgaris strain Hildenborough and no band at 715 nm, characteristic of high-spin Fe3+ complexes in isobacteriochlorins is observed. EPR shows that as isolated the siroheme is in a low-spin ferric state (S=1/2) with g-values at 2.40, 2.30 and 1.88 for the Methanosarcina barkeri enzyme and g-values at 2.44, 2.33 and 1.81 for the Desulfuromonas acetoxidans enzyme. Chemical analysis shows that both proteins contain one siroheme and one [Fe4S4] center per polypeptidic chain. These results suggest that the low molecular weight, low-spin non-heme iron siroheme proteins represent a new homologous class of sulfite reductases common to anaerobic microorganisms.

Original languageEnglish
Pages (from-to)1032-1041
Number of pages10
JournalBiochemical And Biophysical Research Communications
Volume141
Issue number3
DOIs
Publication statusPublished - 30 Dec 1986

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