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19 citations found for Martinez, J
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Two polymorphic crystals of the α-spectrin SH3 domain were obtained using the same crystallization conditions. The hexagonal polymorph represents a more thermodynamically stable form, whereas the orthorhombic form is the kinetically favoured form.
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We present the crystal and molecular structure of two key compounds of a new synthesis strategy for isomers of natural (2S,3R,4S)-4-hydroxyisoleucines, 2,3,5,6,7,8-hexahydro-3-(1-hydroxy-1-methyl-2-oxopropyl)-6,8-methano-7,7,8a-trimethyl-5H-1,4-benzoxazin-2-one, C16H23NO4, and 2,3,5,6,7,8-hexahydro-3-(1-methyl-2-oxopropyl)-6,8-methano-7,7,8a-trimethyl-5H-1,4-benzoxazin-2-one, C16H23NO3. A new optically pure chiral oxazinone auxiliary derived from (1R,2R,5R)-2-hydroxypinan-3-one was used.
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The relative stereochemistry of methyl 6-oxo-5-(5-phenyltetrazol-2-yl)piperidine-2-carboxylate, C14H15N5O3, has been determined. It confirms the cis configuration of the piperidine ring as well as the position of the substituent on the tetrazole ring. The packing of the molecules is influenced by N—H
O and C—H
N hydrogen bonds.
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The crystal structures of two constructs of RC1339/APRc from R. conorii, consisting of either residues 105–231 or 110–231 followed by a His tag, have been determined in three different crystal forms. The monomer of APRc assumes a retropepsin-like fold, but the dimer observed in all crystal forms is entirely different from the canonical dimer of retropepsins.
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The heteroepitaxial AlxGa1-xSb/GaSb (001) growth with different x aluminum content, from 0.05 to 0.2 prepared by Liquid Phase Epitaxy (LPE) is presented. The interest in this study is due to the layers of AlxGa1-xSb systems should be well matched for fabrication of sources and detectors operating in the 1.3-1.6 micron range. The layered structure obtained was characterized mainly by high-resolution X-ray diffraction and reciprocal space mapping. In the case of x = 0.05 aluminum content, the relaxation is minimal, and almost without deviation respect to GaSb. As the aluminum content increases above 0.05, the relaxation is larger and deviation from GaSb substrate too. Crystallographic tilt is detected by a shift of layer diffraction maximum on reciprocal space maps. Deviation changes the intensity of layer respect to substrate peak in rocking curves and hence the estimation of thickness of layer obtained from them. A correction for estimated thickness of layers is obtained from mapping.
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The X-ray crystal structure of human TSG101 UEV domain has been determined at 2.2 Å resolution and refined to an R factor of 18.8%.
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We present here the crystal structure of the title compound, C14H19NO4. It contains O
H—O and N
H—O hydrogen bonds, connecting the molecules into centrosymmetric dimers and into infinite chains.
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We present the crystal and molecular structures of 2,3,6,7,8,8a-hexahydro-6,8-methano-7,7,8a-trimethyl-3-(1-methyl-2-oxopropylidene)-5H-1,4-benzoxazin-2-one, C16H21NO3, (III), and 2,3,6,7,8,8a-hexahydro-3-(2-hydroxy-1-methylpropyl)-6,8-methano-7,7,8a-trimethyl-5H-1,4-benzoxazin-2-one, C16H25NO3, (V). These compounds are two of the four key intermediates in our synthetic route to (2R,3R,4R)-4-hydroxyisoleucine. The two structures provide a full understanding of the stereochemistry in successive steps. This synthesis was based on a new optically pure chiral oxazinone auxiliary derived from (1R,2R,5R)-2-hydroxypinan-3-one.
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We present the crystal and molecular structures of two new N-phthalyl-3-amino-2-arylpropionic acid pantolactonyl ester derivatives with 4-fluorophenyl and 3,4-dimethoxyphenyl as the aryl group, 2,3,4,5-tetrahydro-4,4-dimethyl-2-oxofuran-3-yl 3-phthalimido-2-(4-fluorophenyl)propanoate, C23H20FNO6, and 2,3,4,5-tetrahydro-4,4-dimethyl-2-oxofuran-3-yl 3-phthalimido-2-(3,4-dimethoxyphenyl)propanoate ethyl acetate hemisolvate, C25H25NO8·0.5C4H8O2. This structural study confirms the S configuration of the C2 and validates the stereospecificity of our synthesis strategy.
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There are two symmetry-independent formula units of the title compound, dimethyl 3-benzyl-2-(4-methyl-2,5-dioxoimidazolidin-1-yl)butanedioate, C17H20N2O6, per cell. The two symmetry-independent molecules differ in their configuration and are diastereomers. This structural study confirms a new side reaction during the synthesis of seven-membered cyclopeptides. The stereochemistry of both diastereomers has been established.
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The silaproline-containing dipeptide N-(3,3-dimethyl-1-pivaloyl-1-aza-3-sila-5-cyclopentylcarbonyl)-L-alanine isopropylamide, C17H33N3O3Si, has two independent molecules in the asymmetric unit and each adopts a β-II folded conformation, where the amide on the terminal C interacts intramolecularly with the pivaloyl O atom. The five-membered silaproline ring is Cβ-puckered, an infrequent conformation for the homologous proline ring.
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The crystal and molecular structure of 1-tert-butyl 4-ethyl (2′R,3′R,5′R,2S,3S)-3-bromomethyl-3-hydroxy-2-[(2′-hydroxy-2′,6′,6′-trimethylbicyclo[3.1.1]hept-3′-ylidene)amino]succinate, C21H34BrNO6, is presented. This compound is an intermediate in the new synthetic route to β-substituted β-hydroxyaspartates, which are blockers of glutamate transport.
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Structural studies revealed a proline switch as a novel mechanism for the multidrug-resistant nature of multidrug-resistant clinical isolate 769 HIV-1 protease variants.