RESONANCE RAMAN-STUDY ON THE IRON-SULFUR CENTERS OF DESULFOVIBRIO-GIGAS ALDEHYDE OXIDOREDUCTASE

Resonance Raman spectra of the molybdenum containing aldehyde oxidored uctase from Desulfovibrio gigas were recorded at liquid nitrogen tempe rature with various excitation wavelengths. The spectra indicate that all the iron atoms are organised in [2Fe-2S] type centers consistent w ith cysteine ligations. No vibrational modes involving molybdenum coul d be clearly identified. The features between 280 and 420 cm(-1) are s imilar but different from those of typical plant ferredoxin-like [2Fe- 2S] cluster. The data are consistent with the presence of a plant ferr edoxin-like cluster (center I) and a unique [2Fe-2S] cluster (center I I), as suggested by other spectroscopic studies. The Raman features of center II are different from those of other [2Fe-2S] clusters in prot eins, In addition, a strong peak at ca. 683 cm(-1) which is not presen t in other [2Fe-2S] clusters in proteins, was observed with purple exc itation (406.7-413.1 nm), The peak is assigned to enhanced cysteinyl C -S stretching in center II, suggesting a novel geometry for this cente r.