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]]." />Both mAc and cAc are quite similar in their ACO function. Studies, however, concentrated on <scene name='Aconitase/7acn-sf4/1'>the mitochondrial ACO</scene>. ACO is an excellent system for understanding the role of iron-sulfur-clusters in catalysis. The <scene name='Aconitase/7acn-sf4/2'>(4Fe-4S) cofactor is held in place</scene> by three sulfur atoms belonging to the cysteins-385, -448, and -451 <scene name='Aconitase/7acn-morph/3'>which are bound to three of the four</scene> cluster iron atoms. On activation of the enzyme, <scene name='Aconitase/7acn-morph/4'>a fourth iron atom is included in the cluster</scene>. It can be four-, five-, or six-coordinate, but is constrained to bond to three sulfur atoms of the (4Fe-4S)-cluster with tetrahedral 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.<ref>PMID:8151704</ref>