1aoz
From Proteopedia
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REFINED CRYSTAL STRUCTURE OF ASCORBATE OXIDASE AT 1.9 ANGSTROMS RESOLUTION
Overview
The crystal structure of the fully oxidized form of ascorbate oxidase (EC, 1.10.3.3) from Zucchini has been refined at 1.90 A (1 A = 0.1 nm), resolution, using an energy-restrained least-squares refinement procedure., The refined model, which includes 8764 protein atoms, 9 copper atoms and, 970 solvent molecules, has a crystallographic R-factor of 20.3% for 85,252, reflections between 8 and 1.90 A resolution. The root-mean-square, deviation in bond lengths and bond angles from ideal values is 0.011 A and, 2.99 degrees, respectively. The subunits of 552 residues (70,000 Mr) are, arranged as tetramers with D2 symmetry. One of the dyads is realized by, the crystallographic axis parallel to the c-axis giving one dimer in the, asymmetric unit. The dimer related about this crystallographic axis is, suggested as the dimer present in solution. Asn92 is the attachment site, for one of the two N-linked sugar moieties, which has defined electron, density for the N-linked N-acetyl-glucosamine ring. Each subunit is built, up by three domains arranged sequentially on the polypeptide chain and, tightly associated in space. The folding of all three domains is of a, similar beta-barrel type and related to plastocyanin and azurin. An, analysis of intra- and intertetramer hydrogen bond and van der Waals, interactions is presented. Each subunit has four copper atoms bound as, mononuclear and trinuclear species. The mononuclear copper has two, histidine, a cysteine and a methionine ligand and represents the type-1, copper. It is located in domain 3. The bond lengths of the type-1 copper, centre are comparable to the values for oxidized plastocyanin. The, trinuclear cluster has eight histidine ligands symmetrically supplied from, domain 1 and 3. It may be subdivided into a pair of copper atoms with, histidine ligands whose ligating N-atoms (5 NE2 atoms and one ND1 atom), are arranged trigonal prismatic. The pair is the putative type-3 copper., The remaining copper has two histidine ligands and is the putative, spectroscopic type-2 copper. Two oxygen atoms are bound to the trinuclear, species as OH- or O2- and bridging the putative type-3 copper pair and as, OH- or H2O bound to the putative type-2 copper trans to the copper pair., The bond lengths within the trinuclear copper site are similar to, comparable binuclear model compounds. The putative binding site for the, reducing substrate is close to the type-1 copper.(ABSTRACT TRUNCATED AT, 400 WORDS)
About this Structure
1AOZ is a Single protein structure of sequence from Cucurbita pepo var. melopepo with NAG, CU, C2O and C1O as ligands. Active as L-ascorbate oxidase, with EC number 1.10.3.3 Full crystallographic information is available from OCA.
Reference
Refined crystal structure of ascorbate oxidase at 1.9 A resolution., Messerschmidt A, Ladenstein R, Huber R, Bolognesi M, Avigliano L, Petruzzelli R, Rossi A, Finazzi-Agro A, J Mol Biol. 1992 Mar 5;224(1):179-205. PMID:1548698
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