1apx

CRYSTAL STRUCTURE OF RECOMBINANT ASCORBATE PEROXIDASE

spinqualitylabelsall models 1apx, resolution 2.20Å Show:Asymmetric Unit Biological Assembly Drag the structure with the mouse to rotate   Export Animated Image   Print3D Structural highlights 1apx is a 4 chain structure with sequence from Pisum sativum. Full crystallographic information is available from OCA. For a guided tour on the structure components use FirstGlance. Method: X-ray diffraction, Resolution 2.2Å Ligands: HEM, K Resources: FirstGlance, OCA, PDBe, RCSB, PDBsum, ProSAT Function APX1_PEA Plays a key role in hydrogen peroxide removal. 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 The crystal structure of recombinant pea cytosolic ascorbate peroxidase has been refined to an R = 0.19 for data between 8.0 and 2.2 A resolution and magnitude of F > or = 2 sigma(magnitude of F). The refined model consists of four ascorbate peroxidase monomers consisting of 249 residues per monomer assembled into two homodimers, with one heme group per monomer. The ascorbate peroxidase model confirms that the pea cytosolic enzyme is a noncovalent homodimer held together by a series of ionic interactions arranged around the 2-fold noncrystallographic dimer axis. As expected from the high level of sequence identity (33%), the overall fold of the ascorbate peroxidase monomer closely resembles that of cytochrome c peroxidase. The average root mean square differences for 137 helical alpha-carbon atoms between the four ascorbate peroxidase monomers and cytochrome c peroxidase and for 249 topologically equivalent alpha-carbon atoms are 0.9 and 1.3 A, respectively. The active site structures are also the same, including the hydrogen-bonding interactions between the proximal His ligand, a buried Asp residue, and a Trp residue, whose indole ring is parallel to and in contact with the proximal His ligand just under the heme ring. This proximal Trp residue is thought to be the site of free radical formation in cytochrome c peroxidase compound I and is also essential for enzyme activity. The corresponding Trp in ascorbate peroxidase, Trp179, occupies exactly the same position. The most interesting, and possibly functionally important, difference between the two peroxidases is the presence of a cation binding site in ascorbate peroxidase located approximately 8 A from the alpha-carbon atom of Trp179. Crystal structure of recombinant pea cytosolic ascorbate peroxidase.,Patterson WR, Poulos TL Biochemistry. 1995 Apr 4;34(13):4331-41. PMID:7703247 From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine. See Also Ascorbate peroxidase 3D structures

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