Anthony Noles Sandbox
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Aconitase
Aconitase (PDB 2b3x) catalyzes the reversible isomerization of citrate and isocitrate.
Mechanism of Aconitase
Template:STRUCTURE 2b3x Aconitase contains . This iron sulfur cluster does not participate in redox as most do, but coordinates the OH goup of citrate to facilitate its elimination.[1] It is as this . The rest of the active site is made up of residues Gln72, Asp100, His101, Asp165, Ser166, His167, His147, Glu262, Asn258, Cys358, Cys421, Cys424. Cys358, Cys421, Asn446, Arg447, Arg452, Asp568, Ser642, Ser643, Arg644, Arg580. [2]
Stage 1: Dehydration
First, dehydration of citrate causes a proton and OH group to be removed from only the 'lower arm'.[3] This forms a cis-Aconitate intermediate.
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Stage 2: Rehydration
The second main stage of the reaction is the rehydration of the cis-Aconitate intermediate. This forms isocitrate. It is catalyzed in a stereospecific way such that only one isocitrate stereoisomer is formed. [4]
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Thus, the overall reaction that aconitase catalyzes is:
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References
- ↑ Dupuy J, Volbeda A, Carpentier P, Darnault C, Moulis JM, Fontecilla-Camps JC. Crystal structure of human iron regulatory protein 1 as cytosolic aconitase. Structure. 2006 Jan;14(1):129-39. PMID:16407072 doi:10.1016/j.str.2005.09.009
- ↑ Beinert, H., Kennedy, M. C., Stout, C.D. “Aconitase as Iron−Sulfur Protein, Enzyme, and Iron-Regulatory Protein.” Chem. Rev. 1996, 96, 2335−2373.
- ↑ Voet, Donald, Judith G. Voet, and Charlotte W. Pratt. Fundamentals of Biochemistry Life at the Molecular Level. New York: John Wiley & Sons, 2008. p. 578. Print.
- ↑ Voet, Donald, Judith G. Voet, and Charlotte W. Pratt. Fundamentals of Biochemistry Life at the Molecular Level. New York: John Wiley & Sons, 2008. p. 579. Print.
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