E.p.r. spectra of reduced iron-sulphur centres of the aldehyde oxidoreductase (iron-molybdenum protein) of Desulfovibrio gigas were recorded at X-band and Q-band frequencies and simulated. Results are consistent with the view that only two types of [2Fe-2S] clusters are present, as in eukaryotic molybdenum-containing hydroxylases. The data indicate the Fe/SI centre to be very similar, and the Fe/SII centre somewhat similar, to these centres in the eukaryotic enzymes.
