Single-crystal neutron diffraction: structure of sodium tris(acetato)dioxouranate(1–)

Navaza, A.; Charpin, P.; Vigner, D.; Heger, G.

doi:10.1107/s0108270191003165

Cited by 30 publications

(13 citation statements)

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“…The crystal structure was solved by molecular replacement techniques. The program AMoRe (21) was used to obtain a structure solution for cholesterol oxidase from Streptomyces. The search model used was cholesterol oxidase from B. sterolicum, the structure of which has been refined to 1.8 Å resolution.…”

Section: Methodsmentioning

confidence: 99%

Crystal Structure Determination of Cholesterol Oxidase from Streptomyces and Structural Characterization of Key Active Site Mutants^,

et al. 1999

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Cholesterol oxidase is a monomeric flavoenzyme which catalyzes the oxidation and isomerization of cholesterol to cholest-4-en-3-one. The enzyme interacts with lipid bilayers in order to bind its steroid substrate. The X-ray structure of the enzyme from Brevibacterium sterolicum revealed two loops, comprising residues 78-87 and residues 433-436, which act as a lid over the active site and facilitate binding of the substrate [Vrielink et al. (1991) J. Mol. Biol. 219, 533-554; Li et al. (1993) Biochemistry 32, 11507-11515]. It was postulated that these loops must open, forming a hydrophobic channel between the membrane and the active site of the protein and thus sequestering the cholesterol substrate from the aqueous environment. Here we describe the three-dimensional structure of the homologous enzyme from Streptomyces refined to 1.5 A resolution. Structural comparisons to the enzyme from B. sterolicum reveal significant conformational differences in these loop regions; in particular, a region of the loop comprising residues 78-87 adopts a small amphipathic helical turn with hydrophobic residues directed toward the active site cavity and hydrophilic residues directed toward the external surface of the molecule. It seems reasonable that this increased rigidity reduces the entropy loss that occurs upon binding substrate. Consequently, the Streptomyces enzyme is a more efficient catalyst. In addition, we have determined the structures of three active site mutants which have significantly reduced activity for either the oxidation (His447Asn and His447Gln) or the isomerization (Glu361Gln). Our structural and kinetic data indicate that His447 and Glu361 act as general base catalysts in association with conserved water H2O541 and Asn485. The His447, Glu361, H2O541, and Asn485 hydrogen bond network is conserved among other oxidoreductases. This catalytic tetrad appears to be a structural motif that occurs in flavoenzymes that catalyze the oxidation of unactivated alcohols.

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Section: Methodsmentioning

confidence: 99%

Crystal Structure Determination of Cholesterol Oxidase from Streptomyces and Structural Characterization of Key Active Site Mutants^,

et al. 1999

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“…In most cases, interaction between the uranyl ions UO 2 2+ and the anions of aliphatic monocarboxylic acids L leads to the formation of mononuclear anionic complex units [UO 2 L 3 ] – (Figure ) The anions of monocarboxylic acids in such complex units exhibit the bidentate cyclic coordination mode, which is designated as B 01 according to ref . The resulting structures of compounds of uranyl ions and the anions of aliphatic monocarboxylic acids are usually three dimensional because of electrostatic interactions or hydrogen bonding among the complex ions [UO 2 L 3 ] – and different counterions (for examples, see refs …”

Section: Introductionmentioning

confidence: 99%

Unusual Heteronuclear Uranyl Clusters with Aliphatic Monocarboxylate Ligands and Coordination Modes of Crotonate, Butyrate, and Valerate Ions

et al. 2018

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Two compounds with unusual architectures of uranyl complexes were synthesized and then studied by single-crystal X-ray diffraction and FTIR spectroscopy. Compound Ba 2 [UO 2 (C 3 H 5 COO) 3 ] 4 ·2C 3 H 5 COOH·7H 2 O (I) is constructed of neutral hexanuclear clusters {Ba 2 [UO 2 (C 3 H 5 COO) 3 ] 4 -(C 3 H 5 COOH) 2 (H 2 O) 4 } containing crotonate ions. Compound Sr(H 2 O) 6 {Na[UO 2 (i-C 3 H 7 COO) 3 ] 3 } (II) is constructed of anionic tetranuclear clusters {Na[UO 2 (i-C 3 H 7 COO) 3 ] 3 } 2containing isobutyrate ions. These and other examples of heteronuclear clusters imply that the alkali and alkaline-earth metal atoms in these structures are not just charge-balancing ions, but truly [a]

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“…Analogous results were obtained for the methoxy substituted 2 and hydroxy derivative 3. Three such ligands assemble around one uranyl ion and these complexes have been characterized by 1 H, 13 C NMR, elemental analysis, and mass spectrometry. One notable difference is the solubility of the complex [ i Pr 2 EtNH] + [UO 2 (3) 3 ] À obtained when the hydroxy substituted ligand 3 is treated with UO 2 (NO 3 ) 2 in the presence of the hindered H€ unig's base ( i Pr 2 EtN).…”

Section: Resultsmentioning

confidence: 99%

“…UO 2 2+ is a hard Lewis acid and prefers to interact with hard oxygen donors; accordingly, many carboxylate-containing ligands are known for the uranyl ion. A crystallographic example of planar hexacoordinate uranyl triacetate 13 is shown in Fig. 1.…”

Section: Introductionmentioning

confidence: 99%

Encapsulation of the uranyl dication

et al. 2010

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Single-crystal neutron diffraction: structure of sodium tris(acetato)dioxouranate(1–)

Cited by 30 publications

References 1 publication

Crystal Structure Determination of Cholesterol Oxidase from Streptomyces and Structural Characterization of Key Active Site Mutants^,

Crystal Structure Determination of Cholesterol Oxidase from Streptomyces and Structural Characterization of Key Active Site Mutants^,

Unusual Heteronuclear Uranyl Clusters with Aliphatic Monocarboxylate Ligands and Coordination Modes of Crotonate, Butyrate, and Valerate Ions

Encapsulation of the uranyl dication

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Single-crystal neutron diffraction: structure of sodium tris(acetato)dioxouranate(1–)

Cited by 30 publications

References 1 publication

Crystal Structure Determination of Cholesterol Oxidase from Streptomyces and Structural Characterization of Key Active Site Mutants,

Crystal Structure Determination of Cholesterol Oxidase from Streptomyces and Structural Characterization of Key Active Site Mutants,

Unusual Heteronuclear Uranyl Clusters with Aliphatic Monocarboxylate Ligands and Coordination Modes of Crotonate, Butyrate, and Valerate Ions

Encapsulation of the uranyl dication

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Crystal Structure Determination of Cholesterol Oxidase from Streptomyces and Structural Characterization of Key Active Site Mutants^,

Crystal Structure Determination of Cholesterol Oxidase from Streptomyces and Structural Characterization of Key Active Site Mutants^,