Mössbauer Parameters of Rubredoxin, a One-Iron-Sulfur Protein
Rubredoxins are red, iron-containing redox proteins. They are found in many bacteria and are among the simplest iron proteins known. 1) They typically consist of a polypeptide chain of 50–60 amino acids which binds a single iron atom by means of four characteristically located cysteine residues. The three-dimensional structure of rubredoxin from Clostridium pasteurianum, the particular protein under study here, has been determined by x-ray diffraction.2) It is found that the thiolate sulfurs of the four cysteine residues bind to the iron in a roughly tetóahedral array. The iron-sulfur distances range from 2.05 Å to 2.34 Å according to the x-ray data2), and the local symmetry at the iron site is C1 only. Recent EXAFS studies suggest smaller differences in the Fe-S distances3), but the symmetry is still expected to be very low.
KeywordsSpin Relaxation Internal Field Mossbauer Spectrum Clostridium Pasteurianum Orbital Ground State
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