Characterization of two dissimilatory sulfite reductases from sulfate-reducing bacteria
- Citation:
- Characterization of two dissimilatory sulfite reductases from sulfate-reducing bacteria, Huynh, B., Moura I., Lino A., Moura J., and Legall J. , Hyperfine Interactions, Volume 42, Number 1, p.905-908, (1988)
Abstract:
Mössbauer, EPR, and biochemical techniques were used to characterize two dissimilatory sulfite reductases: desulforubidin from Desulfovibrio baculatus strain DSM 1743 and desulfoviridin from Desulfovibrio gigas . For each molecule of desulforubidin, there are two sirohemes and four [4Fe−4S] clusters. The [4Fe−4S] clusters are in the diamagnetic 2+ oxidation state. The sirohemes are high-spin ferric (S=5/2) and each siroheme is exchanged-coupled to a [4Fe−4S] 2+ cluster. Such an exchange-coupled siroheme-[4Fe−4S] unit has also been found in the assimilatory sulfite reductase from Escherichia coli /1/ and in a low-molecular weight sulfite reductase from Desulfovibrio vulgaris /2/. For each molecule of defulfoviridin, there are two tetrahydroporphyrin groups and four [4Fe−4S] 2+ clusters. To our surprise, we discovered that about 80% of the tetrahydroporphyrin groups, however, do not bind iron.
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