Site-directed mutagenesis iron protein

From One Type to Another Type of Fe-S Cluster. Iron-sulfur clusters, such as [2Fe-2S], [3Fe-4S], and [4Fe-4S], are found in proteins see Iron-Sulfur Proteins). One of the most interesting aspects of the iron-sulfur proteins is their ready conversion from one type to another through chemical oxidation and reduction, pH changes, or site-directed mutagenesis.More importantly, several studies have indicated that some of the cluster conversions are physiologically relevant in that they play important roles in regulation of enzyme activity. 

As mentioned above, a 1 1 stoichiometric relationship between the photooxidized donor, P700 and the reduced terminal acceptors has not yet been established for the PS-I reaction center. As previously noted, the total amount of the recognized terminal acceptors reduced at 15 K is, on average, approximately 74% of the P700 photooxidized. Even more intriguing, in the reconstituted PS-I complexes from either the Cys-14->Asp or Cys-51->Asp mutant PsaC protein, the extent of photoreduction of each intact iron-sulfur cluster at 15 K remained nearly the same as in the wild-type preparation. The presence of the other cluster that was made photochemically inactive by site-directed mutagenesis apparently had no effect on the behavior of the unaltered cluster. 

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