Figure 1. Pyrococcus furiosus heterotetrameric and dimeric soluble hydrogenase I.

(a) Model of predicted cofactor contents of the heterotetrameric form of Pf SHI (taken without modification from Sun et al. [10]) and of the heterodimeric form of SHI that was produced (PF0893-PF0894) in this study that lacks PF0891 and PF0892. In the dimeric form, PF0893 is modified with an N-terminal His₉ tag. The abbreviations used are: CO, carbonyl ligand; CN, cyanide ligand; FAD, flavin adenine dinucleotide; NADP, nicotinamide adenine dinucleotide phosphate. (b) SDS-PAGE of purified heterotetrameric (left lane) and heterodimeric form of SHI (right lane) with molecular masses indicated in kDa.