Resonance Raman spectroscopic evidence for the presence of 4Fe and 3Fe centers in Pseudomonas ovalis ferredoxin and Mycobacterium smegmatis ferredoxin

Indolepyruvate ferredoxin oxidoreductase: An oxygen-sensitive iron-sulfur enzyme from the hyperthermophilic archaeon Thermococcus profundus

Thermococcus profundus is a strictly anaerobic sulfur-dependent archaeon that grows optimally at 80°C by peptide fermentation. Indolepyruvate ferredoxin oxidoreductase (IOR), an enzyme involved in the peptide fermentation pathway, was purified to homogeneity from the archaeon under strictly anaerobic conditions. The maximal activity was obtained above the boiling temperature of water (105°C), with a half-life of 62min at 100°C and 20min at 105°C. IOR was oxygen-sensitive with a half-life of 7h at 25°C under aerobic conditions. The specific activity of T. profundus IOR was found to be dependent on the number of [4Fe-4S] clusters in the enzyme.

A novel 6Fe (2 x [3Fe-4S]) ferredoxin from Mycobacterium smegmatis

A novel ferredoxin was purified from Mycobacterium smegmatis by a series of hydrophobic chromatographies in the presence of high concentrations of ammonium sulfate and sodium chloride. The ferredoxin exhibited the same peptide map and N-terminal amino acid sequence as the known 7Fe ferredoxin from the same bacterium. On the other hand, this ferredoxin was found to contain approximately 6 Fe/mol ferredoxin and was also shown to contain only [3Fe-4S] clusters by resonance Raman spectroscopy, indicating that it is a novel 6Fe ferredoxin which contains two [3Fe-4S] clusters.