Iron-sulfur clusters and cysteine distribution in a ferredoxin from Azotobacter vinelandii

James B. Howard, Thomas Lorsbach, Lawrence Que

Research output: Contribution to journalArticlepeer-review

9 Scopus citations


In 80% dimethyl sulfoxide/H2O, Azotobacter ferredoxin FeS clusters can be extruded with benzene thiol. The extruded clusters have an absorption spectra maximum at 458 nm which is characteristic of 4Fe4S centers. The amino terminal sequence of the Azotobacter ferredoxin has 7 of the 8 Cys residues at residue numbers 8, 11, 16, 20, 24, 39 and 42. Except for Cys 24, all of these residues can be correlated to homologous Cys residues in other bacterial ferredoxins. Although two thirds of the first 45 residues are identical to or conservative replacements for the first 43 residues of other bacterial ferredoxins, the insertion of Cys-24 indicates a major change in the environment of one of the two 4Fe4S clusters.

Original languageEnglish (US)
Pages (from-to)582-588
Number of pages7
JournalBiochemical and Biophysical Research Communications
Issue number2
StatePublished - May 17 1976

Bibliographical note

Funding Information:
by NSF Grant


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