Resonance Raman spectroscopy of Azotobacter vinelandii ferredoxin I. Vibrational features of the [3Fe-3S] cluster.

Low temperature resonance Raman spectra have been obtained for Clostridium pasteurianum and Bacillus stearothermophilus ferredoxins. Several heretofore undetected fundamental bands have been observed and these data have been used to discriminate the vibrational contribution of the [3Fe-3S] cluster to the spectrum of Azotobacter vinelandii ferredoxin I. The vibrational features of the [3Fe-3S] core distinguish it from other 3-iron clusters and imply structural differences among this class of iron-sulfur clusters.