1dao

File:1dao.gif

spinqualitylabelsall models 1dao, resolution 3.2Å Show:Asymmetric Unit Biological Assembly Drag the structure with the mouse to rotate   Export Animated Image

COVALENT ADDUCT OF D-AMINO ACID OXIDASE FROM PIG KIDNEY WITH 3-METHYL-2-OXO-VALERIC ACID

OverviewOverview

D-Amino acid oxidase (DAAO) is the prototype of the flavin-containing, oxidases. It catalyzes the oxidative deamination of various D-amino acids, ranging from D-Ala to D-Trp. We have carried out the X-ray analysis of, reduced DAAO in complex with the reaction product imino tryptophan (iTrp), and of the covalent adduct generated by the photoinduced reaction of the, flavin with 3-methyl-2-oxobutyric acid (kVal). These structures were, solved by combination of 8-fold density averaging and least-squares, refinement techniques. The FAD redox state of DAAO crystals was assessed, by single-crystal polarized absorption microspectrophotometry. iTrp binds, to the reduced enzyme with the N, C alpha, C, and C beta atoms positioned, 3.8 A from the re side of the flavin. The indole side chain points away, from the cofactor and is bound in the active site through a rotation of, Tyr224. This residue plays a crucial role in that it adapts its, conformation to the size of the active site ligand, providing the enzyme, with the plasticity required for binding a broad range of substrates. The, iTrp binding mode is fully consistent with the proposal, inferred from the, analysis of the native DAAO structure, that substrate oxidation occurs via, direct hydride transfer from the C alpha to the flavin N5 atom. In this, regard, it is remarkable that, even in the presence of the bulky iTrp, ligand, the active center is made solvent inaccessible by loop 216-228., This loop is thought to switch between the "closed" conformation observed, in the crystal structures and an "open" state required for substrate, binding and product release. Loop closure is likely to have a role in, catalysis by increasing the hydrophobicity of the active site, thus making, the hydride transfer reaction more effective. Binding of kVal leads to, keto acid decarboxylation and formation of a covalent bond between the, keto acid C alpha and the flavin N5 atoms. Formation of this acyl adduct, results in a nonplanar flavin, characterized by a 22 degrees angle between, the pyrimidine and benzene rings. Thus, in addition to an adaptable, substrate binding site, DAAO has the ability to bind a highly distorted, cofactor. This ability is relevant for the enzyme's function as a highly, efficient oxidase.

About this StructureAbout this Structure

1DAO is a Single protein structure of sequence from Sus scrofa with FAB as ligand. Active as D-amino-acid oxidase, with EC number 1.4.3.3 Structure known Active Sites: FAA, FAB, FAC, FAD, FAE, FAF, FAG and FAH. Full crystallographic information is available from OCA.

ReferenceReference

Active site plasticity in D-amino acid oxidase: a crystallographic analysis., Todone F, Vanoni MA, Mozzarelli A, Bolognesi M, Coda A, Curti B, Mattevi A, Biochemistry. 1997 May 13;36(19):5853-60. PMID:9153426

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