1ami | pdb_00001ami

STERIC AND CONFORMATIONAL FEATURES OF THE ACONITASE MECHANISM

spinqualitylabelsall models 1ami, resolution 2.00Å Show:Asymmetric Unit Biological Assembly Drag the structure with the mouse to rotate   Export Animated Image   Print3D Structural highlights 1ami is a 1 chain structure with sequence from Bos taurus. Full crystallographic information is available from OCA. For a guided tour on the structure components use FirstGlance. Method: X-ray diffraction, Resolution 2Å Ligands: MIC Resources: FirstGlance, OCA, PDBe, RCSB, PDBsum, ProSAT Function ACON_BOVIN Catalyzes the isomerization of citrate to isocitrate via cis-aconitate. Evolutionary Conservation Check, as determined by ConSurfDB. You may read the explanation of the method and the full data available from ConSurf. Publication Abstract from PubMed Crystal structures of mitochondrial aconitase with alpha-methylisocitrate and with sulfate bound have been solved and refined at 2.0 A resolution with R factors of 18.2 and 16.8%, respectively. The steric factors and conformational effects observed in both new structures support the proposed mechanism for the overall reaction catalyzed by aconitase. The alternate substrate alpha-methylisocitrate is derived from alpha-methyl-cis-aconitate during crystallization and is observed to bind in the active site in a manner very similar to that observed for isocitrate. The methyl group is accommodated by favorable contact with Ile-425. However, the other potential hydration product of alpha-methyl-cis-aconitate, alpha-methylcitrate, cannot be accommodated in the active site due to steric conflict of the methyl group with Asp-165. The results are consistent with the requirement that cis-aconitate must bind in two ways, in the citrate mode and in the isocitrate mode. Crystals of aconitase with sulfate bound are isomorphous to those with isocitrate bound. However, the structure displays significant conformational changes, providing a model for the substrate-free state of enzyme. Three water molecules bind in place of the C alpha- and C beta-hydroxyl and carboxyl groups of isocitrate, while sulfate binds in place of the C gamma-carboxyl group. Side chains of Ser-642 and Arg-447 in the active site rotate to pair with other side chains in the absence of substrate. The new conformation of Arg-447 triggers a concerted set of shifts which transmits conformational change to the surface of the protein, 30 A from the active site. In the absence of substrate, a chain segment containing the [4Fe-4S] ligand Cys-358 also shifts, resulting in the net translation and reorientation of the Fe-S cluster. Steric and conformational features of the aconitase mechanism.,Lauble H, Stout CD Proteins. 1995 May;22(1):1-11. PMID:7675781 From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine. See Also Aconitase 3D structures

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