1frf: Difference between revisions

[[Image:1frf.gif|left|200px]]<br /><applet load="1frf" size="350" color="white" frame="true" align="right" spinBox="true"  

The role of the high potential [3Fe-4S]1+,0 cluster of [NiFe] hydrogenase from Desulfovibrio species located halfway between the proximal and distal low potential [4Fe-4S]2+,1+ clusters has been investigated by using site-directed mutagenesis. Proline 238 of Desulfovibrio fructosovorans [NiFe] hydrogenase, which occupies the position of a potential ligand of the lacking fourth Fe-site of the [3Fe-4S] cluster, was replaced by a cysteine residue. The properties of the mutant enzyme were investigated in terms of enzymatic activity, EPR, and redox properties of the iron-sulfur centers and crystallographic structure. We have shown on the basis of both spectroscopic and x-ray crystallographic studies that the [3Fe-4S] cluster of D. fructosovorans hydrogenase was converted into a [4Fe-4S] center in the P238 mutant. The [3Fe-4S] to [4Fe-4S] cluster conversion resulted in a lowering of approximately 300 mV of the midpoint potential of the modified cluster, whereas no significant alteration of the spectroscopic and redox properties of the two native [4Fe-4S] clusters and the NiFe center occurred. The significant decrease of the midpoint potential of the intermediate Fe-S cluster had only a slight effect on the catalytic activity of the P238C mutant as compared with the wild-type enzyme. The implications of the results for the role of the high-potential [3Fe-4S] cluster in the intramolecular electron transfer pathway are discussed.

1FRF is a [http://en.wikipedia.org/wiki/Protein_complex Protein complex] structure of sequences from [http://en.wikipedia.org/wiki/Desulfovibrio_fructosovorans Desulfovibrio fructosovorans] with <scene name='pdbligand=FE:'>FE</scene>, <scene name='pdbligand=NI:'>NI</scene>, <scene name='pdbligand=MG:'>MG</scene>, <scene name='pdbligand=SF4:'>SF4</scene> and <scene name='pdbligand=F3S:'>F3S</scene> as [http://en.wikipedia.org/wiki/ligands ligands]. Active as [http://en.wikipedia.org/wiki/Ferredoxin_hydrogenase Ferredoxin hydrogenase], with EC number [http://www.brenda-enzymes.info/php/result_flat.php4?ecno=1.12.7.2 1.12.7.2] Full crystallographic information is available from [http://oca.weizmann.ac.il/oca-bin/ocashort?id=1FRF OCA].  

[[Category: Fontecilla, J C.]]

[[Category: Hatchikian, E C.]]

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