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  • 1
    Electronic Resource
    Electronic Resource
    Amino/aromatic interactions (1993)
    [s.l.] : Nature Publishing Group
    Nature 366 (1993), S. 413-413 
    Details
    ISSN: 1476-4687
    Source: Nature Archives 1869 - 2009
    Topics: Biology , Chemistry and Pharmacology , Medicine , Natural Sciences in General , Physics
    Notes: [Auszug] SIR - Rodham et al.{ detailed both experimental and theoretical investigations of the structure of the ammonia/benzene complex. Following the identification of an amino/aromatic hydrogen bond in SH2 domain/peptide binding by Waksman et al.2, there has been a resurgence of interest in such ...
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1038/366413a0
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  • 2
    Electronic Resource
    Electronic Resource
    Multipole-based calculation of the polarization energy (1996)
    Springer
    Theoretical chemistry accounts 94 (1996), S. 287-295 
    Details
    ISSN: 1432-2234
    Keywords: Polarization energy ; Charge transfer energy ; Distributed Multipole Analysis ; Gaussian multipoles
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract A novel method for calculating the polarization energy of a biomolecular complex is developed. It is based on direct calculation of the interaction between the unperturbed charge distribution of one molecule and the perturbed charge distribution of the other. This “multipole-based polarization energy” is shown to include charge transfer. The method can alternatively incorporate Gaussian multipoles in place of the usual distributed point multipoles. This definition of the polarization energy is also used as the basis of a partitioning scheme for the total supermolecule interaction energy. Results are presented for the formamide/formaldehyde complex.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00213713
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  • 3
    Electronic Resource
    Electronic Resource
    Diisophorone and related compounds. Part 19 Synthesis and reactions of 6,8-dibromodiisophorones (1988)
    Springer
    Monatshefte für Chemie 119 (1988), S. 195-213 
    Details
    ISSN: 1434-4475
    Keywords: 6,8-Dibromodiisophorones, synthesis of, ring A aromatisation of ; Ring A-aromatised tricyclo[7.3.1.02,7]tridecanes
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Zusammenfassung Neuartige 6,8-Dibrom-Abkömmlinge des Diisophor-2(7)-en-1-ol-3-ons und der entsprechenden 1-Carbonsäure (als Methylester) sind durch Einwirkung von 2 mol N-Bromsuccinimid auf die betreffende Grundverbindung leicht zugänglich. Bei der Umsetzung des 6,8-Dibromketols mit Alkalien entsteht 6-Methyl-5-nordiisophora-2(7),3,5-trien-1,3,8-triol, unter gleichzeitiger 8-Substituierung und Ring-A-Aromatisierung. Acetolyse und Methanolyse ergeben die entsprechenden 8-Acetoxy- und 8-Methoxy-Verbindungen. Die 6,8-Dibrom-1-carbonsäure reagiert analog, mit weiterer Möglichkeit zur 1,3-Lacton-Bildung. Die13C-Kernresonanz-und Massenspektren der neuen Verbindungen stehen mit den Strukturzuordnungen im Einklang.
    Notes: Abstract Novel 6,8-dibromo-derivatives of diisophor-2(7)-en-1-ol-3-one and the corresponding 1-carboxylic acid methyl ester are readily accessible by the action of 2 mol of N-bromosuccinimide on the respective parent compounds. Treatment with alkali converts the 6,8-dibromo-ketol, by a simultaneous 8-substitution and ring A-aromatisation, into 6-methyl-5-nordiisophora-2(7),3,5-triene-1,3,8-triol; acetolysis and methanolysis produce the corresponding 8-acetoxy- and 8-methoxy-compounds. The 6,8-dibromo-1-carboxylic acid reacts analogously, with the added option of 1,3-lactone formation. The assigned13C-nmr spectra and fragmentation patterns of the new compounds are in accord with their proposed formulation.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00809594
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  • 4
    Electronic Resource
    Electronic Resource
    Modelling the interactions of protein side-chains (1995)
    Springer
    Molecular engineering 5 (1995), S. 89-105 
    Details
    ISSN: 1572-8951
    Keywords: Molecular modelling ; protein side-chains ; hydrogen bonding ; electrostatic energy ; distributed multipole analysis ; amino/aromatic interactions ; intermolecular perturbation theory
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract The study of small model molecules containing the relevant functional groups can help us to understand the interactions between side-chains in proteins.Ab initio quantum chemical techniques allow the interactions between the model molecules to be studied with much greater accuracy than is possible for an entire protein, where the use of simple empirical potentials is the norm. In particular, the use ofab initio methods on model molecules permits us to incorporate the atom-atom anisotropic directionality of these interactions. We survey various methods of obtaining the components of theab initio interaction energy. These are then applied to three systems of biological interest. The first of these is the arginine/aspartate pair found in salt bridges, which involves hydrogen bonding between two charged species. Secondly, we look at the arginine/phosphotyrosine interaction found in complexes between SH2 domains and peptide ligands: here we find that the arginine/phosphate part of the interaction is energetically far more important than the arginine/aromatic part. Finally, we describe a detailed study of amino/aromatic interactions in proteins: ‘unconventional hydrogen bonds’ are found to be remarkably uncommon relative to stacked geometries, and the reasons for this are examined.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00999581
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  • 5
    Electronic Resource
    Electronic Resource
    Gaussian multipoles in practice: Electrostatic energies for intermolecular potentials (1994)
    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Computational Chemistry 15 (1994), S. 1187-1198 
    Details
    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 method is presented for calculating the total electrostatic interaction energies between molecules from ab initio monomer wave functions. This approach differs from existing methods, such as Stone's distributed multipole analysis (DMA), in including the short-range penetration energy as well as the long-range multipolar energy. The monomer charge densities are expressed as distributed series of atom-centered functions which we call Gaussian multipoles; these are analogous to the distributed point multipoles used in DMA. Our procedure has been encoded in the GMUL program. Calculations have been performed on the formamide/formaldehyde complex, a model system for N—H … O hydrogen bonding in biological molecules, and also on guanidinium/benzene, modeling amino/aromatic interactions in proteins. We find that the penetration energy can be significant, especially in its contribution to the variation of the electrostatic energy with interaction geometry. A hybrid method, which uses Gaussian multipoles for short-range atom pair interactions and point multipoles for long-range ones, allows the electrostatic energies, including penetration, to be calculated at a much reduced cost. We also note that the penetration energy may provide the best route to an atom-atom anisotropic model for the exchange-repulsion energy in intermolecular potentials. © 1994 by John Wiley & Sons, Inc.
    Additional Material: 4 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/jcc.540151102
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  • 6
    Electronic Resource
    Electronic Resource
    The nature of the N — H…O=C hydrogen bond: An intermolecular perturbation theory study of the formamide/formaldehyde complex (1990)
    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Computational Chemistry 11 (1990), S. 1217-1233 
    Details
    ISSN: 0192-8651
    Keywords: Computational Chemistry and Molecular Modeling ; Biochemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Computer Science
    Notes: We have used Hayes-Stone Intermolecular Perturbation Theory (IMPT) to study the variation with distance and orientation of the various components of the interaction energy of the N — H…O = C hydrogen bonded trans- formamide/formaldehyde complex, a model system for hydrogen bonding in proteins. The directionality of the total interaction energy is similar to that of the electrostatic component alone. We have analysed our data in terms of two model atom-atom intermolecular potentials, using an isotropic functional form and an anisotropic one. The anisotropic form gives an excellent representation of the IMPT potential energy surface, considerably better than the isotropic model, and is comprised entirely of theoretically justified, physically meaningful terms.
    Additional Material: 7 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/jcc.540111014
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