Aconitase: Difference between revisions

<applet load=7acn scene='Aconitase/7acn-sf4/1' size='400' frame='true' align='left' caption="Mitochondrial aconitase from pig, PDB [[7acn]]." />The bulk of citrate cycle processing happens in mitochondria and so, studies concentrated on <scene name='Aconitase/7acn-sf4/1'>the mitochondrial ACO</scene>. The <scene name='Aconitase/7acn-sf4-3cys/1'>(4Fe-4S) cofactor is held in place</scene> by three sulfur atoms belonging to the cysteins-385, -448, and -451 which are bound to three of the four cluster iron atoms. The fourth, Fe4, is free to bind; it can be four-, five-, or six-coordinate, but is constrained to bond to three sulfur atoms of the (4Fe-4S)-cluster with terahedral geometry. Thus, Fe4 is free to bind one, two, or three partners, in this reaction always oxygen atoms belonging to other molecules. As Fe4 is not bound very fast to the cluster, it moves quite a bit around in the process of bonding and debonding.