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Title
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Structure of Azotobacter vinelandii 7Fe ferredoxin. Amino acid sequence and electron density maps of residues.
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Authors
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J.B.Howard,
T.W.Lorsbach,
D.Ghosh,
K.Melis,
C.D.Stout.
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Ref.
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J Biol Chem, 1983,
258,
508-522.
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PubMed id
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Abstract
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The complete amino acid sequence of the 7Fe ferredoxin from Azotobacter
vinelandii (Av Fd) was determined by repetitive Edman degradation of the whole
protein and of peptides derived from CNBr cleavage or chymotrypsin digestion.
The sequence was confirmed by the 2A electron density maps for the residues
calculated with difference Fourier coefficients. The density maps for all
residues are included in the paper. Av Fd has several important differences with
the clostridial-type ferredoxins: (i) Av Fd is 106 residues (versus 55-60 for
other bacterial ferredoxins); (ii) Av Fd has 9 cysteines, one of which (residue
24) is not homologous with the bacterial ferredoxins; (iii) Av Fd has 2 extra
residues between 2 cysteines (residues 11 and 16) homologous to cysteines in the
bacterial ferredoxins; and (iv) Av Fd has the unique sequence
-Cys-Val-Glu-Val-Cys- (residues 16-20) which are two of the ligands of the
3Fe:3S center. These sequence features are compared to the sequences of various
ferredoxin groups. Structure predictions for other suspected 7Fe ferredoxins are
discussed.
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