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  • 1
    Electronic Resource
    Electronic Resource
    Oxford [u.a.] : International Union of Crystallography (IUCr)
    Acta crystallographica 48 (1992), S. 2271-2273 
    ISSN: 1600-5759
    Source: Crystallography Journals Online : IUCR Backfile Archive 1948-2001
    Topics: Chemistry and Pharmacology , Geosciences , Physics
    Type of Medium: Electronic Resource
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  • 2
    Electronic Resource
    Electronic Resource
    Copenhagen : International Union of Crystallography (IUCr)
    Acta crystallographica 53 (1997), S. 976-983 
    ISSN: 1600-5740
    Source: Crystallography Journals Online : IUCR Backfile Archive 1948-2001
    Topics: Chemistry and Pharmacology , Geosciences , Physics
    Notes: The structural characteristics of ortho- and meta-substituted phenylpiperazines have been investigated in order to understand their actions at the serotonin 5-HT2c receptor. The crystal structures of the 4-methylated analogues of two phenylpiperazines that are already known as 5-HT2c ligands, 1-(1-naphthyl)-4-methylpiperazine (1NMP) and 1-[(3-trifluoromethyl)phenyl]-4-methylpiperazine (TFMPMP), and those of two novel 5-HT2c ligands, 1-(2-methoxyphenyl)piperazine (oMPP) and 1-(3-methoxyphenyl)piperazine (mMPP), are determined. Molecular mechanics calculations are performed to calculate the energy profiles of six phenylpiperazines for rotation about the central phenyl–nitrogen bond. The activities of several phenylpiperazines, in combination with their crystal structures and conformational characteristics, lead to the hypothesis that the conformation for which the piperazine ring and the phenyl ring are approximately co-planar should be the 5-HT2c receptor `activating' conformation. This hypothesis is then used to predict the activities of the two novel 5-HT2c ligands oMPP and mMPP. oMPP is predicted to be an antagonist at this receptor, whereas mMPP is predicted to be an agonist. As this prediction was confirmed by in vitro and in vivo tests, the proposed conformation is very likely to be responsible for the activation of the 5-HT2c receptor.
    Type of Medium: Electronic Resource
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  • 3
    ISSN: 0192-8651
    Keywords: Computational Chemistry and Molecular Modeling ; Biochemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Computer Science
    Notes: A new method for the estimation of torsion barriers and its application to conformational analysis is presented. This method, the ToBaD method (method of the torsion barrier derivative), makes use of crystal structure data. It is based on the assumption that the conformation of a compound in the crystalline phase must be very close to a (local) minimum energy conformation of this compound in the gas phase. The ToBaD method is demonstrated for the rotation of the phenyl-N bond in N,N-dimethylaniline. Two geometries of this compound are handled separately: one in which the nitrogen substituents are in a pyramidal or sp3 geometry, and the other in which the nitrogen atom and its substituents are coplanar (the sp2 geometry). It is predicted, by means of the ToBaD method, that for both geometries the conformation in which the nitrogen lone pair or p orbital is perpendicular to the aromatic ring is the lowest energy conformation. © 1994 by John Wiley & Sons, Inc.
    Additional Material: 4 Ill.
    Type of Medium: Electronic Resource
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  • 4
    Electronic Resource
    Electronic Resource
    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Computational Chemistry 18 (1997), S. 638-645 
    ISSN: 0192-8651
    Keywords: Chemistry ; Theoretical, Physical and Computational Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Computer Science
    Notes: In this article a new method is described to superimpose molecules using a crystallographic Fourier transform approach. Superimposed molecules, among other purposes, serve as a basis for three-dimensional (3D) QSAR analyses in drug design and therefore an objective and reproducible method of molecule alignment is of major importance. Fourier data are generated for hypothetical crystals of cubic symmetry for the compounds under consideration. A Patterson-density-based similarity index is used to optimize rotational alignment of the molecules. After optimization of rotational orientation, an electron density derived similarity index is used to further optimize overlap of electron density as a function of translation of the molecules. Both similarity indices are maximized by a simple optimization routine, thus enabling automated superposition. The use of Fourier space offers several advantages. First, rotational and translational parameters can be optimized separately, thus providing a small parameter space. Second, a limited number of data already provide an adequate, continuous description of the electron (or Patterson) density distribution. Third, crystallography provides simple methods to calculate the Fourier transforms that are needed. The resolution of the Patterson (electron) density representation used for superposition can be varied in a straightforward manner. Results are shown for the superposition of two antiviral agents, 2rs1 and 2r04; the dihydrofolate reductase ligands, methotrexate and dihydrofolate; and a set of three ε-thrombin inhibitors. © 1997 by John Wiley & Sons, Inc.
    Additional Material: 4 Ill.
    Type of Medium: Electronic Resource
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