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  • 1
    Electronic Resource
    Electronic Resource
    Chirality of intermediates in thiamin catalysis: structure of (+)-2-(1-hydroxyethyl)-3,4-dimethyl-5-(2-hydroxyethyl)thiazolium iodide, the absolute stereochemistry of the enantiomers of 2-(1-hydroxyethyl)thiamin, and enzymic reaction of the diphosphates (1987)
    s.l. : American Chemical Society
    Journal of the American Chemical Society 109 (1987), S. 618-620 
    Details
    ISSN: 1520-5126
    Source: ACS Legacy Archives
    Topics: Chemistry and Pharmacology
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1021/ja00236a070
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  • 2
    Electronic Resource
    Electronic Resource
    The hydrated potassium complex of the ionophore monensin A (1987)
    s.l. : American Chemical Society
    Journal of the American Chemical Society 109 (1987), S. 2163-2165 
    Details
    ISSN: 1520-5126
    Source: ACS Legacy Archives
    Topics: Chemistry and Pharmacology
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1021/ja00241a038
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  • 3
    Electronic Resource
    Electronic Resource
    Phase changes in T3R_3^{\rm f} human insulin: temperature or pressure induced? (2001)
    Copenhagen : International Union of Crystallography (IUCr)
    Acta crystallographica 57 (2001), S. 1091-1100 
    Details
    ISSN: 1399-0047
    Source: Crystallography Journals Online : IUCR Backfile Archive 1948-2001
    Topics: Chemistry and Pharmacology , Geosciences , Physics
    Notes: The structure of T3R_3^{\rm f} hexameric human insulin has been determined at 100 K from two different crystals at 1.2 and 1.3 Å resolution and refined to residuals of 0.169 and 0.176, respectively. Owing to a phase change, the c axis is double its room-temperature value and the asymmetric unit contains two independent TRf insulin dimers. Compared with the orientation in the room-temperature structure, one dimer undergoes a rotation about the c axis of −5°, while the second is rotated +4°. A superposition of the backbone atoms of the two independent dimers shows that the Cα atoms of five residues within the Rf-state monomers are displaced by more than 1.0 Å; smaller displacements are observed for the T-state monomers. Four zinc ions lie on the crystallographic threefold axis and each forms bonds to three symmetry-related HisB10 Nε2 atoms from the T- and Rf-state trimers. While three of the zinc ions are tetrahedrally coordinated with a chloride ion completing the coordination sphere, mixed tetrahedral/octahedral coordination is observed for one of the T-state zinc ions. The three symmetry-related `phenolic binding sites' in one hexamer contain water molecules and a glycerol molecule, but the same sites in the second hexamer are occupied by a zinc ion coordinated to an alternate conformation of HisB10, a symmetry-related HisB5 and two chloride ions. Two additional and partially occupied zinc ion sites are observed at the interface between the two independent dimers. One zinc ion is coordinated by a T-state HisB5 of one dimer, an R-state HisB5 of the second dimer and two water molecules; the second zinc ion is coordinated by an alternate side-chain conformation of the T-state HisB5 and three water molecules. The carboxyl group of one GluB13 side chain, which exists in two discrete conformations, appears to be protonated, because short contacts exist to a second carboxyl group or to a carbonyl O atom.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1107/S0907444901007685
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  • 4
    Electronic Resource
    Electronic Resource
    R6 hexameric insulin complexed with m-cresol or resorcinol (2000)
    Copenhagen : International Union of Crystallography (IUCr)
    Acta crystallographica 56 (2000), S. 1541-1548 
    Details
    ISSN: 1399-0047
    Source: Crystallography Journals Online : IUCR Backfile Archive 1948-2001
    Topics: Chemistry and Pharmacology , Geosciences , Physics
    Notes: The structures of three R6 human insulin hexamers have been determined. Crystals of monoclinic m-cresol–insulin, monoclinic resorcinol–insulin and rhombohedral m-cresol–insulin diffracted to 1.9, 1.9 and 1.78 Å, respectively, and have been refined to residuals of 0.195, 0.179 and 0.200, respectively. In all three structures, a phenolic derivative is found to occupy the phenolic binding site, where it forms hydrogen bonds to the carbonyl O atom of CysA6 and the N atom of CysA11. Two additional phenolic derivative binding sites were identified within or between hexamers. The structures of all three hexamers are nearly identical, although a large displacement of the N-terminus of one B chain in both monoclinic structures results from coordination to a sodium ion which is located between symmetry-related hexamers. Other minor differences in structure arise from differences in packing in the monoclinic cell compared with the rhombohedral cell. Based upon the differences in conformation of the GluB13 side chains in T6, T3R^{\rm f}_{3} and R6 hexamers, the deprotonation of these side chains appears to be associated with the T→R conformational transition.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1107/S0907444900012749
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  • 5
    Electronic Resource
    Electronic Resource
    Structure of the insecticidal bacterial δ-endotoxin Cry3Bb1 of Bacillus thuringiensis (2001)
    Copenhagen : International Union of Crystallography (IUCr)
    Acta crystallographica 57 (2001), S. 1101-1109 
    Details
    ISSN: 1399-0047
    Source: Crystallography Journals Online : IUCR Backfile Archive 1948-2001
    Topics: Chemistry and Pharmacology , Geosciences , Physics
    Notes: The coleopteran-active δ-endotoxin Cry3Bb1 from Bacillus thuringiensis (Bt) strain EG7231 is uniquely toxic to Diabrotica undecimpunctata, the Southern corn rootworm, while retaining activity against Leptinotarsa decemlineata, the Colorado potato beetle. The crystal structure of the δ-endotoxin Cry3Bb1 has been refined using data collected to 2.4 Å resolution, with a residual R factor of 17.5% and an Rfree of 25.3%. The structure is made up of three domains: I, a seven-helix bundle (residues 64–294); II, a three-sheet domain (residues 295–502); and III, a β-sandwich domain (residues 503–652). The monomers in the orthorhombic C2221 crystal lattice form a dimeric quaternary structure across a crystallographic twofold axis, with a channel formed involving interactions between domains I and III. There are 23 hydrogen bonds between the two monomers conferring structural stability on the dimer. It has been demonstrated that Cry3Bb1 and the similar toxin Cry3A form oligomers in solution. The structural results presented here indicate that the interactions between domains I and III could be responsible for the initial higher order structure and have implications for the biological activity of these toxins. There are seven additional single amino-acid residues in the sequence of Cry3Bb1 compared with that of Cry3A; one in domain I, two in domain II and four in domain III, which also shows the largest conformational difference between the two proteins. These changes can be implicated in the selectivity differences noted for these two δ-endotoxins.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1107/S0907444901008186
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  • 6
    Electronic Resource
    Electronic Resource
    Determination of a protein structure by iodination: the structure of iodinated acetylxylan esterase (1999)
    Copenhagen : International Union of Crystallography (IUCr)
    Acta crystallographica 55 (1999), S. 779-784 
    Details
    ISSN: 1399-0047
    Source: Crystallography Journals Online : IUCR Backfile Archive 1948-2001
    Topics: Chemistry and Pharmacology , Geosciences , Physics
    Notes: Enzymatic and non-enzymatic iodination of the amino acid tyrosine is a well known phenomenon. The iodination technique has been widely used for labeling proteins. Using high-resolution X-ray crystallographic techniques, the chemical and three-dimensional structures of iodotyrosines formed by non-enzymatic incorporation of I atoms into tyrosine residues of a crystalline protein are described. Acetylxylan esterase (AXE II; 207 amino-acid residues) from Penicillium purpurogenum has substrate specificities towards acetate esters of D-xylopyranose residues in xylan and belongs to a new class of α/β hydrolases. The crystals of the enzyme are highly ordered, tightly packed and diffract to better than sub-ångström resolution at 85 K. The iodination technique has been utilized to prepare an isomorphous derivative of the AXE II crystal. The structure of the enzyme determined at 1.10 Å resolution exclusively by normal and anomalous scattering from I atoms, along with the structure of the iodinated complex at 1.80 Å resolution, demonstrate the formation of covalent bonds between I atoms and C atoms at ortho positions to the hydroxyl groups of two tyrosyl moieties, yielding iodotyrosines.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1107/S0907444999000244
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  • 7
    Electronic Resource
    Electronic Resource
    Structure of rat transthyretin (rTTR) complex with thyroxine at 2.5 Å resolution: first non-biased insight into thyroxine binding reveals different hormone orientation in two binding sites (2001)
    Copenhagen : International Union of Crystallography (IUCr)
    Acta crystallographica 57 (2001), S. 1061-1070 
    Details
    ISSN: 1399-0047
    Source: Crystallography Journals Online : IUCR Backfile Archive 1948-2001
    Topics: Chemistry and Pharmacology , Geosciences , Physics
    Notes: The first observation of the unique environment for thyroxine (T4) binding in tetrameric rat transthyretin (rTTR) is reported as determined by X-ray diffraction. These data revealed different modes of hormone binding in the two unique hormone-binding sites in the rat TTR tetramer channel. Differences in the orientation of thyroxine and the position of water molecules in the two binding sites further suggest a mechanism for the docking pathway of the hormone into the channel of TTR. Crystals of the rat transthyretin–thyroxine complex are isomorphous with those reported for apo rTTR and crystallized in the tetragonal space group P43212 with four independent TTR monomeric subunits in the asymmetric part of the crystal lattice. Data were collected to 2.5 Å resolution and the structure was refined to R = 20.9% for 15 384 data in the resolution range 12–2.5 Å. Similar to human TTR, the rat protein is also a 54 000 Da tetramer with four identical polypeptide chains of 127 amino-acid residues. Of the 22 amino-acid residues which differ between the human and rat sequences, none are in the thyroxine-binding domains. Analysis of these structural data reveals that the tertiary structure is similar to that of hTTR, with only small differences in the flexible loop regions on the surface of the structure. Conformational changes of the amino acids in the channel result in a hydrogen-bonded network that connects the two binding domains, in contrast to the hydrogen bonds formed along the tetramer interface in the apo transthyretin structure. These changes suggest a mechanism for the signal transmission between thyroxine-binding domains.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1107/S0907444901007235
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  • 8
    Electronic Resource
    Electronic Resource
    Crystal and molecular structure of aN(2)-benzyl-1,3-disubstituted-1,2,3,4-tetrahydro-β-carboline (1990)
    Springer
    Journal of chemical crystallography 20 (1990), S. 109-115 
    Details
    ISSN: 1572-8854
    Source: Springer Online Journal Archives 1860-2000
    Topics: Geosciences , Physics
    Notes: Abstract (1R,3S)-2-Benzyl-3-methoxycarbonyl-1-methylcarboxymethyl-1,2,3,4-tetrahydro-9H-pyrido [3,4-b] indole, C23H24N2O4, was synthesized by a modified Pictet-Spengler reaction, and its crystal and molecular structure determined by single crystal X-ray diffraction methods. The crystals are monoclinic:P21 (No. 4),a=11.336(1),b=8.919(1),c=10.314(1)Å,β=100.81(1)°,Z=2. The structure has been solved by direct methods, and refined toR=0.041 for 2203 observed reflections. The six-membered heterocyclic ring is in a half-chair conformation, and the substituents at C(3) and C(5) occupy axial and equatorial positions respectively. The CH2Ph group attached to N(4) is in the generally less favoured axial position. The nitrogen atom of the indole system forms an intermolecular hydrogen bond with the carbonyl oxygen of the CH2CO2 Me group, the N⋯O distance being 2.995(3)Å.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01160961
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  • 9
    Electronic Resource
    Electronic Resource
    Absolute configuration and conformation of the pure opioid antagonist (+)-2,9α-dimethyl-5-(m-hydroxyphenyl)morphan (1992)
    New York, NY [u.a.] : Wiley-Blackwell
    Chirality 4 (1992), S. 377-383 
    Details
    ISSN: 0899-0042
    Keywords: crystal structure ; molecular mechanics ; MM2-87 ; phenylmorphan ; phenyl-equatorial ; opioid ligand model ; μ-receptors ; K-receptors ; Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: (+)-2,9α-Dimethyl-5-(m-hydroxyphenyl)morphan is the only phenylmorphan analog whose affinity for opioid K-receptors is greater than its affinity for opioid κ-receptors. Pharmacologically, the compound is a pure opioid antagonist devoid of agonist activity in in vivo assays of antinociception. The absolute configuration of the compound has been determined to be (1R,5S,9R) from an X-ray crystallographic study of the chloride salt. Thus, the absolute configuration corresponds to that of the atypical opioid agonist (-)-phenylmorphan while the weak atypical agonist (-)-2,9α-dimethyl-5-(m-hydroxyphenyl)morphan corresponds to the potent morphine-like (+)-phenylmorphan. The preferred orientations of the phenyl ring for the two stereoisomers were determined using the molecular mechanics program MM2-87 and found to vary from that of the two parent compounds. The atypical properties of the two 9α-methyl analogs is consistent with an opioid ligand model which proposes that morphine-like properties require a particular range of phenyl orientations. There was good agreement between the structure obtained from X-ray crystallography and computed with the MM2-87 program. © 1992 Wiley-Liss, Inc.
    Additional Material: 4 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/chir.530040608
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  • 10
    Electronic Resource
    Electronic Resource
    Purification and crystallization of insecticidal δ-endotoxin CryIIIB2 from Bacillus thuringiensis (1992)
    New York, NY : Wiley-Blackwell
    Proteins: Structure, Function, and Genetics 14 (1992), S. 324-324 
    Details
    ISSN: 0887-3585
    Keywords: Bacillus thuringiensis ; insecticidal ; δ-endotoxin ; crystallization ; Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Medicine
    Notes: CryIIIB2, an insecticidal protein from Bacillus thuringiensis has been crystallized from 0.6 M NaBr and HEPES buffer at pH 7.0 and X-ray diffraction data collected on a native crystal to 2.4 Å. The insecticidal protein was obtained from a Bacillus thuringiensis (Bt) strain EG7231. Crystals of the endotoxin are orthorhombic, space group C2221, with unit cell dimensions of a = 122.44, b = and c = Å. A unit cell contains one molecule of the 67,000 Da endotoxin per asymmetric unit. © 1992 Wiley-Liss, Inc.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/prot.340140217
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