Structure for the Ferredoxin from the cyanobacteria Anabaena (PDB ID= 1FXA) at t
ID: 3165050 • Letter: S
Question
Structure for the Ferredoxin from the cyanobacteria Anabaena (PDB ID= 1FXA) at the RSCB Protein databank. Ferredoxin contains a single iron-sulfur cluster. The RCSB Protein Data Bank can be found at: http://www.rcsb.org/pdb
1.) Select backbone as the scheme. Are both the iron atoms buried to the same extent? Which is closer to the surface and thus would have a higher reduction potential?
Ligand Explorer to answer the following questions.
2.) Examine the [2Fe-2S] cluster in Chain A. What amino acids (name and sequence numbers) is each Fe in the cluster coordinated to? (Hint turn on metal interactions to have a look.) How are these amino acids interacting with the Fe ions?
A) What are all the Fe-S distances in the cluster and how do they compare to the distances between the Fe ion and the coordinated amino acids?
B) Using the angle measure selection under the Analysis menu, measure the bond angles around each of the Fe ions. Supply those angles on a diagram .
C) What is the approximate coordination geometry for each of the Fe ions?
D) Four of the eight atoms shown above fall in a plane. Circle the planar portion of the
structure.
Explanation / Answer
2.2Fe-2S contains two irons two inorganic sulfides and usually 4 cysteine residues . They mediate electron transfer in a range of metabolic reactions,
Iron ions in these complexes cycle between Fe2+( reduced) and Fe3+ (oxidised) states.
Iron sulfur cluster generally undergo oxidation-reduction reactions with out releasing or binding protons.