The iron-sulfur composition of the active site of hydrogenase from Desulfovibrio vulgaris (Hildenborough) deduced from its subunit structure and total iron-sulfur content

The subunit composition and Fe/S content of nine different batches of D. vulgaris (H) hydrogenase have been determined. SDS-PAGE and FPLC show the enzyme to be an αβ dimer consistent with the molecular mass of 46 + 13.5 kDa recently inferred from the nucleotide sequence. Based on this molecular mass and a protein determination calibrated on tryptophan + tyrosine content, the enzyme is found to contain 14–16 Fe and 12–14 S 2−, and ϵ 400 = 45 mM −1cm −1. It is suggested that the active site of this bidirectional hydrogenase is not a [4Fe-4S] cluster, but rather is a novel cluster comprised of approx. 6 Fe and 6 S 2−. Hydrogenase Iron-sulfur cluster (Desulfovibrio vulgaris)